OpenSim.Modules.EMail/src/MailKit/MailFolder.cs

//
// MailFolder.cs
//
// Author: Jeffrey Stedfast <jestedfa@microsoft.com>
//
// Copyright (c) 2013-2020 .NET Foundation and Contributors
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//

using System;
using System.IO;
using System.Threading;
using System.Collections;
using System.Threading.Tasks;
using System.Collections.Generic;

using MimeKit;

using MailKit.Search;

namespace MailKit {
	/// <summary>
	/// An abstract mail folder implementation.
	/// </summary>
	/// <remarks>
	/// An abstract mail folder implementation.
	/// </remarks>
	public abstract class MailFolder : IMailFolder
	{
		/// <summary>
		/// The bit mask of settable flags.
		/// </summary>
		/// <remarks>
		/// Only flags in the list of settable flags may be set on a message by the client.
		/// </remarks>
		protected static readonly MessageFlags SettableFlags = MessageFlags.Answered | MessageFlags.Deleted |
			MessageFlags.Draft | MessageFlags.Flagged | MessageFlags.Seen;

		IMailFolder parent;

		/// <summary>
		/// Initialize a new instance of the <see cref="MailKit.MailFolder"/> class.
		/// </summary>
		/// <remarks>
		/// Initializes a new instance of the <see cref="MailKit.MailFolder"/> class.
		/// </remarks>
		protected MailFolder ()
		{
		}

		/// <summary>
		/// Get an object that can be used to synchronize access to the folder.
		/// </summary>
		/// <remarks>
		/// <para>Gets an object that can be used to synchronize access to the folder.</para>
		/// </remarks>
		/// <value>The sync root.</value>
		public abstract object SyncRoot {
			get;
		}

		/// <summary>
		/// Get the parent folder.
		/// </summary>
		/// <remarks>
		/// Root-level folders do not have a parent folder.
		/// </remarks>
		/// <value>The parent folder.</value>
		public IMailFolder ParentFolder {
			get { return parent; }
			internal protected set {
				if (value == parent)
					return;

				if (parent != null)
					parent.Renamed -= OnParentFolderRenamed;

				parent = value;

				if (parent != null)
					parent.Renamed += OnParentFolderRenamed;
			}
		}

		/// <summary>
		/// Get the folder attributes.
		/// </summary>
		/// <remarks>
		/// Gets the folder attributes.
		/// </remarks>
		/// <value>The folder attributes.</value>
		public FolderAttributes Attributes {
			get; internal protected set;
		}

		/// <summary>
		/// Get the annotation access level.
		/// </summary>
		/// <remarks>
		/// If annotations are supported, this property can be used to determine whether or not
		/// the <see cref="IMailFolder"/> supports reading and writing annotations.
		/// </remarks>
		public AnnotationAccess AnnotationAccess {
			get; internal protected set;
		}

		/// <summary>
		/// Get the supported annotation scopes.
		/// </summary>
		/// <remarks>
		/// If annotations are supported, this property can be used to determine which
		/// annotation scopes are supported by the <see cref="IMailFolder"/>.
		/// </remarks>
		public AnnotationScope AnnotationScopes {
			get; internal protected set;
		}

		/// <summary>
		/// Get the maximum size of annotation values supported by the folder.
		/// </summary>
		/// <remarks>
		/// If annotations are supported, this property can be used to determine the
		/// maximum size of annotation values supported by the <see cref="IMailFolder"/>.
		/// </remarks>
		public uint MaxAnnotationSize {
			get; internal protected set;
		}

		/// <summary>
		/// Get the permanent flags.
		/// </summary>
		/// <remarks>
		/// <para>The permanent flags are the message flags that will persist between sessions.</para>
		/// <para>If the <see cref="MessageFlags.UserDefined"/> flag is set, then the folder allows
		/// storing of user-defined (custom) message flags.</para>
		/// </remarks>
		/// <value>The permanent flags.</value>
		public MessageFlags PermanentFlags {
			get; protected set;
		}

		/// <summary>
		/// Get the accepted flags.
		/// </summary>
		/// <remarks>
		/// The accepted flags are the message flags that will be accepted and persist
		/// for the current session. For the set of flags that will persist between
		/// sessions, see the <see cref="PermanentFlags"/> property.
		/// </remarks>
		/// <value>The accepted flags.</value>
		public MessageFlags AcceptedFlags {
			get; protected set;
		}

		/// <summary>
		/// Get the directory separator.
		/// </summary>
		/// <remarks>
		/// Gets the directory separator.
		/// </remarks>
		/// <value>The directory separator.</value>
		public char DirectorySeparator {
			get; protected set;
		}

		/// <summary>
		/// Get the read/write access of the folder.
		/// </summary>
		/// <remarks>
		/// Gets the read/write access of the folder.
		/// </remarks>
		/// <value>The read/write access.</value>
		public FolderAccess Access {
			get; internal protected set;
		}

		/// <summary>
		/// Get whether or not the folder is a namespace folder.
		/// </summary>
		/// <remarks>
		/// Gets whether or not the folder is a namespace folder.
		/// </remarks>
		/// <value><c>true</c> if the folder is a namespace folder; otherwise, <c>false</c>.</value>
		public bool IsNamespace {
			get; protected set;
		}

		/// <summary>
		/// Get the full name of the folder.
		/// </summary>
		/// <remarks>
		/// This is the equivalent of the full path of a file on a file system.
		/// </remarks>
		/// <value>The full name of the folder.</value>
		public string FullName {
			get; protected set;
		}

		/// <summary>
		/// Get the name of the folder.
		/// </summary>
		/// <remarks>
		/// This is the equivalent of the file name of a file on the file system.
		/// </remarks>
		/// <value>The name of the folder.</value>
		public string Name {
			get; protected set;
		}

		/// <summary>
		/// Get the unique identifier for the folder, if available.
		/// </summary>
		/// <remarks>
		/// <para>Gets a unique identifier for the folder, if available. This is useful for clients
		/// implementing a message cache that want to track the folder after it is renamed by another
		/// client.</para>
		/// <note type="note">This property will only be available if the server supports the
		/// <a href="https://tools.ietf.org/html/rfc8474">OBJECTID</a> extension.</note>
		/// </remarks>
		/// <value>The unique folder identifier.</value>
		public string Id {
			get; protected set;
		}

		/// <summary>
		/// Get a value indicating whether the folder is subscribed.
		/// </summary>
		/// <remarks>
		/// Gets a value indicating whether the folder is subscribed.
		/// </remarks>
		/// <value><c>true</c> if the folder is subscribed; otherwise, <c>false</c>.</value>
		public bool IsSubscribed {
			get { return (Attributes & FolderAttributes.Subscribed) != 0; }
		}

		/// <summary>
		/// Get a value indicating whether the folder is currently open.
		/// </summary>
		/// <remarks>
		/// Gets a value indicating whether the folder is currently open.
		/// </remarks>
		/// <value><c>true</c> if the folder is currently open; otherwise, <c>false</c>.</value>
		public abstract bool IsOpen {
			get;
		}

		/// <summary>
		/// Get a value indicating whether the folder exists.
		/// </summary>
		/// <remarks>
		/// Gets a value indicating whether the folder exists.
		/// </remarks>
		/// <value><c>true</c> if the folder exists; otherwise, <c>false</c>.</value>
		public bool Exists {
			get { return (Attributes & FolderAttributes.NonExistent) == 0; }
		}

		/// <summary>
		/// Get whether or not the folder supports mod-sequences.
		/// </summary>
		/// <remarks>
		/// <para>Gets whether or not the folder supports mod-sequences.</para>
		/// <para>If mod-sequences are not supported by the folder, then all of the APIs that take a modseq
		/// argument will throw <see cref="System.NotSupportedException"/> and should not be used.</para>
		/// </remarks>
		/// <value><c>true</c> if supports mod-sequences; otherwise, <c>false</c>.</value>
		[Obsolete ("Use Supports (FolderFeature.ModSequences) instead.")]
		public bool SupportsModSeq {
			get { return Supports (FolderFeature.ModSequences); }
		}

		/// <summary>
		/// Get the highest mod-sequence value of all messages in the mailbox.
		/// </summary>
		/// <remarks>
		/// Gets the highest mod-sequence value of all messages in the mailbox.
		/// </remarks>
		/// <value>The highest mod-sequence value.</value>
		public ulong HighestModSeq {
			get; protected set;
		}

		/// <summary>
		/// Get the UID validity.
		/// </summary>
		/// <remarks>
		/// <para>UIDs are only valid so long as the UID validity value remains unchanged. If and when
		/// the folder's <see cref="UidValidity"/> is changed, a client MUST discard its cache of UIDs
		/// along with any summary information that it may have and re-query the folder.</para>
		/// <para>This value will only be set after the folder has been opened.</para>
		/// </remarks>
		/// <value>The UID validity.</value>
		public uint UidValidity {
			get; protected set;
		}

		/// <summary>
		/// Get the UID that the folder will assign to the next message that is added.
		/// </summary>
		/// <remarks>
		/// This value will only be set after the folder has been opened.
		/// </remarks>
		/// <value>The next UID.</value>
		public UniqueId? UidNext {
			get; protected set;
		}

		/// <summary>
		/// Get the maximum size of a message that can be appended to the folder.
		/// </summary>
		/// <remarks>
		/// <para>Gets the maximum size of a message that can be appended to the folder.</para>
		/// <note type="note">If the value is not set, then the limit is unspecified.</note>
		/// </remarks>
		/// <value>The append limit.</value>
		public uint? AppendLimit {
			get; protected set;
		}

		/// <summary>
		/// Get the size of the folder.
		/// </summary>
		/// <remarks>
		/// <para>Gets the size of the folder in bytes.</para>
		/// <note type="note">If the value is not set, then the size is unspecified.</note>
		/// </remarks>
		/// <value>The size.</value>
		public ulong? Size {
			get; protected set;
		}

		/// <summary>
		/// Get the index of the first unread message in the folder.
		/// </summary>
		/// <remarks>
		/// This value will only be set after the folder has been opened.
		/// </remarks>
		/// <value>The index of the first unread message.</value>
		public int FirstUnread {
			get; protected set;
		}

		/// <summary>
		/// Get the number of unread messages in the folder.
		/// </summary>
		/// <remarks>
		/// <para>Gets the number of unread messages in the folder.</para>
		/// <note type="note">This value will only be set after calling
		/// <see cref="Status(StatusItems, System.Threading.CancellationToken)"/>
		/// with <see cref="StatusItems.Unread"/>.</note>
		/// </remarks>
		/// <value>The number of unread messages.</value>
		public int Unread {
			get; protected set;
		}

		/// <summary>
		/// Get the number of recently added messages in the folder.
		/// </summary>
		/// <remarks>
		/// <para>Gets the number of recently delivered messages in the folder.</para>
		/// <note type="note">This value will only be set after calling
		/// <see cref="Status(StatusItems, System.Threading.CancellationToken)"/>
		/// with <see cref="StatusItems.Recent"/> or by opening the folder.</note>
		/// </remarks>
		/// <value>The number of recently added messages.</value>
		public int Recent {
			get; protected set;
		}

		/// <summary>
		/// Get the total number of messages in the folder.
		/// </summary>
		/// <remarks>
		/// <para>Gets the total number of messages in the folder.</para>
		/// <note type="note">This value will only be set after calling
		/// <see cref="Status(StatusItems, System.Threading.CancellationToken)"/>
		/// with <see cref="StatusItems.Count"/> or by opening the folder.</note>
		/// </remarks>
		/// <value>The total number of messages.</value>
		public int Count {
			get; protected set;
		}

		/// <summary>
		/// Get the threading algorithms supported by the folder.
		/// </summary>
		/// <remarks>
		/// Get the threading algorithms supported by the folder.
		/// </remarks>
		/// <value>The supported threading algorithms.</value>
		public abstract HashSet<ThreadingAlgorithm> ThreadingAlgorithms { get; }

		/// <summary>
		/// Determine whether or not a <see cref="MailFolder"/> supports a feature.
		/// </summary>
		/// <remarks>
		/// Determines whether or not a <see cref="MailFolder"/> supports a feature.
		/// </remarks>
		/// <param name="feature">The desired feature.</param>
		/// <returns><c>true</c> if the feature is supported; otherwise, <c>false</c>.</returns>
		public abstract bool Supports (FolderFeature feature);

		/// <summary>
		/// Opens the folder using the requested folder access.
		/// </summary>
		/// <remarks>
		/// <para>This variant of the <see cref="Open(FolderAccess,System.Threading.CancellationToken)"/>
		/// method is meant for quick resynchronization of the folder. Before calling this method,
		/// the <see cref="MailStore.EnableQuickResync(CancellationToken)"/> method MUST be called.</para>
		/// <para>You should also make sure to add listeners to the <see cref="MessagesVanished"/> and
		/// <see cref="MessageFlagsChanged"/> events to get notifications of changes since
		/// the last time the folder was opened.</para>
		/// </remarks>
		/// <returns>The <see cref="FolderAccess"/> state of the folder.</returns>
		/// <param name="access">The requested folder access.</param>
		/// <param name="uidValidity">The last known <see cref="UidValidity"/> value.</param>
		/// <param name="highestModSeq">The last known <see cref="HighestModSeq"/> value.</param>
		/// <param name="uids">The last known list of unique message identifiers.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="access"/> is not a valid value.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// The quick resynchronization feature has not been enabled.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support the quick resynchronization feature.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract FolderAccess Open (FolderAccess access, uint uidValidity, ulong highestModSeq, IList<UniqueId> uids, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously opens the folder using the requested folder access.
		/// </summary>
		/// <remarks>
		/// <para>This variant of the <see cref="OpenAsync(FolderAccess,System.Threading.CancellationToken)"/>
		/// method is meant for quick resynchronization of the folder. Before calling this method,
		/// the <see cref="MailStore.EnableQuickResync(CancellationToken)"/> method MUST be called.</para>
		/// <para>You should also make sure to add listeners to the <see cref="MessagesVanished"/> and
		/// <see cref="MessageFlagsChanged"/> events to get notifications of changes since
		/// the last time the folder was opened.</para>
		/// </remarks>
		/// <returns>The <see cref="FolderAccess"/> state of the folder.</returns>
		/// <param name="access">The requested folder access.</param>
		/// <param name="uidValidity">The last known <see cref="UidValidity"/> value.</param>
		/// <param name="highestModSeq">The last known <see cref="HighestModSeq"/> value.</param>
		/// <param name="uids">The last known list of unique message identifiers.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="access"/> is not a valid value.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// The quick resynchronization feature has not been enabled.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support the quick resynchronization feature.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<FolderAccess> OpenAsync (FolderAccess access, uint uidValidity, ulong highestModSeq, IList<UniqueId> uids, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Open the folder using the requested folder access.
		/// </summary>
		/// <remarks>
		/// Opens the folder using the requested folder access.
		/// </remarks>
		/// <returns>The <see cref="FolderAccess"/> state of the folder.</returns>
		/// <param name="access">The requested folder access.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="access"/> is not a valid value.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract FolderAccess Open (FolderAccess access, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously open the folder using the requested folder access.
		/// </summary>
		/// <remarks>
		/// Asynchronously opens the folder using the requested folder access.
		/// </remarks>
		/// <returns>The <see cref="FolderAccess"/> state of the folder.</returns>
		/// <param name="access">The requested folder access.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="access"/> is not a valid value.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<FolderAccess> OpenAsync (FolderAccess access, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Close the folder, optionally expunging the messages marked for deletion.
		/// </summary>
		/// <remarks>
		/// Closes the folder, optionally expunging the messages marked for deletion.
		/// </remarks>
		/// <param name="expunge">If set to <c>true</c>, expunge.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void Close (bool expunge = false, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously close the folder, optionally expunging the messages marked for deletion.
		/// </summary>
		/// <remarks>
		/// Asynchronously closes the folder, optionally expunging the messages marked for deletion.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="expunge">If set to <c>true</c>, expunge.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task CloseAsync (bool expunge = false, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Create a new subfolder with the given name.
		/// </summary>
		/// <remarks>
		/// Creates a new subfolder with the given name.
		/// </remarks>
		/// <returns>The created folder.</returns>
		/// <param name="name">The name of the folder to create.</param>
		/// <param name="isMessageFolder"><c>true</c> if the folder will be used to contain messages; otherwise <c>false</c>.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="name"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="name"/> is empty.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// The <see cref="DirectorySeparator"/> is nil, and thus child folders cannot be created.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IMailFolder Create (string name, bool isMessageFolder, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously create a new subfolder with the given name.
		/// </summary>
		/// <remarks>
		/// Asynchronously creates a new subfolder with the given name.
		/// </remarks>
		/// <returns>The created folder.</returns>
		/// <param name="name">The name of the folder to create.</param>
		/// <param name="isMessageFolder"><c>true</c> if the folder will be used to contain messages; otherwise <c>false</c>.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="name"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="name"/> is empty.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// The <see cref="DirectorySeparator"/> is nil, and thus child folders cannot be created.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IMailFolder> CreateAsync (string name, bool isMessageFolder, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Create a new subfolder with the given name.
		/// </summary>
		/// <remarks>
		/// Creates a new subfolder with the given name.
		/// </remarks>
		/// <returns>The created folder.</returns>
		/// <param name="name">The name of the folder to create.</param>
		/// <param name="specialUses">A list of special uses for the folder being created.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="name"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="specialUses"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="name"/> is empty.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// The <see cref="DirectorySeparator"/> is nil, and thus child folders cannot be created.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailService"/> does not support the creation of special folders.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IMailFolder Create (string name, IEnumerable<SpecialFolder> specialUses, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously create a new subfolder with the given name.
		/// </summary>
		/// <remarks>
		/// Asynchronously creates a new subfolder with the given name.
		/// </remarks>
		/// <returns>The created folder.</returns>
		/// <param name="name">The name of the folder to create.</param>
		/// <param name="specialUses">A list of special uses for the folder being created.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="name"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="specialUses"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="name"/> is empty.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// The <see cref="DirectorySeparator"/> is nil, and thus child folders cannot be created.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailService"/> does not support the creation of special folders.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IMailFolder> CreateAsync (string name, IEnumerable<SpecialFolder> specialUses, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Create a new subfolder with the given name.
		/// </summary>
		/// <remarks>
		/// Creates a new subfolder with the given name.
		/// </remarks>
		/// <returns>The created folder.</returns>
		/// <param name="name">The name of the folder to create.</param>
		/// <param name="specialUse">The special use for the folder being created.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="name"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="name"/> is empty.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// The <see cref="DirectorySeparator"/> is nil, and thus child folders cannot be created.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailService"/> does not support the creation of special folders.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual IMailFolder Create (string name, SpecialFolder specialUse, CancellationToken cancellationToken = default (CancellationToken))
		{
			return Create (name, new [] { specialUse }, cancellationToken);
		}

		/// <summary>
		/// Asynchronously create a new subfolder with the given name.
		/// </summary>
		/// <remarks>
		/// Asynchronously creates a new subfolder with the given name.
		/// </remarks>
		/// <returns>The created folder.</returns>
		/// <param name="name">The name of the folder to create.</param>
		/// <param name="specialUse">The special use for the folder being created.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="name"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="name"/> is empty.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// The <see cref="DirectorySeparator"/> is nil, and thus child folders cannot be created.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailService"/> does not support the creation of special folders.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task<IMailFolder> CreateAsync (string name, SpecialFolder specialUse, CancellationToken cancellationToken = default (CancellationToken))
		{
			return CreateAsync (name, new [] { specialUse }, cancellationToken);
		}

		/// <summary>
		/// Rename the folder.
		/// </summary>
		/// <remarks>
		/// Renames the folder.
		/// </remarks>
		/// <param name="parent">The new parent folder.</param>
		/// <param name="name">The new name of the folder.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="parent"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="name"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="parent"/> does not belong to the <see cref="IMailStore"/>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="name"/> is not a legal folder name.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// The folder cannot be renamed (it is either a namespace or the Inbox).
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void Rename (IMailFolder parent, string name, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously rename the folder.
		/// </summary>
		/// <remarks>
		/// Asynchronously renames the folder.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="parent">The new parent folder.</param>
		/// <param name="name">The new name of the folder.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="parent"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="name"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="parent"/> does not belong to the <see cref="IMailStore"/>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="name"/> is not a legal folder name.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// The folder cannot be renamed (it is either a namespace or the Inbox).
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task RenameAsync (IMailFolder parent, string name, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Delete the folder.
		/// </summary>
		/// <remarks>
		/// Deletes the folder.
		/// </remarks>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// The folder cannot be deleted (it is either a namespace or the Inbox).
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void Delete (CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously delete the folder.
		/// </summary>
		/// <remarks>
		/// Asynchronously deletes the folder.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// The folder cannot be deleted (it is either a namespace or the Inbox).
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task DeleteAsync (CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Subscribe to the folder.
		/// </summary>
		/// <remarks>
		/// Subscribes to the folder.
		/// </remarks>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void Subscribe (CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously subscribe to the folder.
		/// </summary>
		/// <remarks>
		/// Asynchronously subscribes to the folder.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task SubscribeAsync (CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Unsubscribe from the folder.
		/// </summary>
		/// <remarks>
		/// Unsubscribes from the folder.
		/// </remarks>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void Unsubscribe (CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously unsubscribe from the folder.
		/// </summary>
		/// <remarks>
		/// Asynchronously unsubscribes from the folder.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task UnsubscribeAsync (CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Get the subfolders.
		/// </summary>
		/// <remarks>
		/// <para>Gets the subfolders as well as queries the server for the status of the requested items.</para>
		/// <para>When the <paramref name="items"/> argument is non-empty, this has the equivalent functionality
		/// of calling <see cref="GetSubfolders(bool,System.Threading.CancellationToken)"/> and then calling
		/// <see cref="Status(StatusItems,System.Threading.CancellationToken)"/> on each of the returned folders.</para>
		/// </remarks>
		/// <returns>The subfolders.</returns>
		/// <param name="items">The status items to pre-populate.</param>
		/// <param name="subscribedOnly">If set to <c>true</c>, only subscribed folders will be listed.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<IMailFolder> GetSubfolders (StatusItems items, bool subscribedOnly = false, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously get the subfolders.
		/// </summary>
		/// <remarks>
		/// <para>Asynchronously gets the subfolders as well as queries the server for the status of the requested items.</para>
		/// <para>When the <paramref name="items"/> argument is non-empty, this has the equivalent functionality
		/// of calling <see cref="GetSubfoldersAsync(bool,System.Threading.CancellationToken)"/> and then calling
		/// <see cref="StatusAsync(StatusItems,System.Threading.CancellationToken)"/> on each of the returned folders.</para>
		/// </remarks>
		/// <returns>The subfolders.</returns>
		/// <param name="items">The status items to pre-populate.</param>
		/// <param name="subscribedOnly">If set to <c>true</c>, only subscribed folders will be listed.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<IMailFolder>> GetSubfoldersAsync (StatusItems items, bool subscribedOnly = false, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Get the subfolders.
		/// </summary>
		/// <remarks>
		/// Gets the subfolders.
		/// </remarks>
		/// <returns>The subfolders.</returns>
		/// <param name="subscribedOnly">If set to <c>true</c>, only subscribed folders will be listed.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual IList<IMailFolder> GetSubfolders (bool subscribedOnly = false, CancellationToken cancellationToken = default (CancellationToken))
		{
			return GetSubfolders (StatusItems.None, subscribedOnly, cancellationToken);
		}

		/// <summary>
		/// Asynchronously get the subfolders.
		/// </summary>
		/// <remarks>
		/// Asynchronously gets the subfolders.
		/// </remarks>
		/// <returns>The subfolders.</returns>
		/// <param name="subscribedOnly">If set to <c>true</c>, only subscribed folders will be listed.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task<IList<IMailFolder>> GetSubfoldersAsync (bool subscribedOnly = false, CancellationToken cancellationToken = default (CancellationToken))
		{
			return GetSubfoldersAsync (StatusItems.None, subscribedOnly, cancellationToken);
		}

		/// <summary>
		/// Get the specified subfolder.
		/// </summary>
		/// <remarks>
		/// Gets the specified subfolder.
		/// </remarks>
		/// <returns>The subfolder.</returns>
		/// <param name="name">The name of the subfolder.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="name"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="name"/> is either an empty string or contains the <see cref="DirectorySeparator"/>.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The requested folder could not be found.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IMailFolder GetSubfolder (string name, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously get the specified subfolder.
		/// </summary>
		/// <remarks>
		/// Asynchronously gets the specified subfolder.
		/// </remarks>
		/// <returns>The subfolder.</returns>
		/// <param name="name">The name of the subfolder.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="name"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="name"/> is either an empty string or contains the <see cref="DirectorySeparator"/>.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The requested folder could not be found.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IMailFolder> GetSubfolderAsync (string name, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Force the server to flush its state for the folder.
		/// </summary>
		/// <remarks>
		/// Forces the server to flush its state for the folder.
		/// </remarks>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void Check (CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously force the server to flush its state for the folder.
		/// </summary>
		/// <remarks>
		/// Asynchronously forces the server to flush its state for the folder.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task CheckAsync (CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Update the values of the specified items.
		/// </summary>
		/// <remarks>
		/// <para>Updates the values of the specified items.</para>
		/// <para>The <see cref="Status(StatusItems, System.Threading.CancellationToken)"/> method
		/// MUST NOT be used on a folder that is already in the opened state. Instead, other ways
		/// of getting the desired information should be used.</para>
		/// <para>For example, a common use for the <see cref="Status(StatusItems,System.Threading.CancellationToken)"/>
		/// method is to get the number of unread messages in the folder. When the folder is open, however, it is
		/// possible to use the <see cref="MailFolder.Search(MailKit.Search.SearchQuery, System.Threading.CancellationToken)"/>
		/// method to query for the list of unread messages.</para>
		/// </remarks>
		/// <param name="items">The items to update.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support the STATUS command.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void Status (StatusItems items, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously update the values of the specified items.
		/// </summary>
		/// <remarks>
		/// <para>Updates the values of the specified items.</para>
		/// <para>The <see cref="Status(StatusItems, System.Threading.CancellationToken)"/> method
		/// MUST NOT be used on a folder that is already in the opened state. Instead, other ways
		/// of getting the desired information should be used.</para>
		/// <para>For example, a common use for the <see cref="Status(StatusItems,System.Threading.CancellationToken)"/>
		/// method is to get the number of unread messages in the folder. When the folder is open, however, it is
		/// possible to use the <see cref="MailFolder.Search(MailKit.Search.SearchQuery, System.Threading.CancellationToken)"/>
		/// method to query for the list of unread messages.</para>
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="items">The items to update.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support the STATUS command.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task StatusAsync (StatusItems items, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Get the complete access control list for the folder.
		/// </summary>
		/// <remarks>
		/// Gets the complete access control list for the folder.
		/// </remarks>
		/// <returns>The access control list.</returns>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support the ACL extension.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract AccessControlList GetAccessControlList (CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously get the complete access control list for the folder.
		/// </summary>
		/// <remarks>
		/// Asynchronously gets the complete access control list for the folder.
		/// </remarks>
		/// <returns>The access control list.</returns>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support the ACL extension.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<AccessControlList> GetAccessControlListAsync (CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Get the access rights for a particular identifier.
		/// </summary>
		/// <remarks>
		/// Gets the access rights for a particular identifier.
		/// </remarks>
		/// <returns>The access rights.</returns>
		/// <param name="name">The identifier name.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="name"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support the ACL extension.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract AccessRights GetAccessRights (string name, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously get the access rights for a particular identifier.
		/// </summary>
		/// <remarks>
		/// Asynchronously gets the access rights for a particular identifier.
		/// </remarks>
		/// <returns>The access rights.</returns>
		/// <param name="name">The identifier name.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="name"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support the ACL extension.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<AccessRights> GetAccessRightsAsync (string name, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Get the access rights for the current authenticated user.
		/// </summary>
		/// <remarks>
		/// Gets the access rights for the current authenticated user.
		/// </remarks>
		/// <returns>The access rights.</returns>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support the ACL extension.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract AccessRights GetMyAccessRights (CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously get the access rights for the current authenticated user.
		/// </summary>
		/// <remarks>
		/// Asynchronously gets the access rights for the current authenticated user.
		/// </remarks>
		/// <returns>The access rights.</returns>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support the ACL extension.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<AccessRights> GetMyAccessRightsAsync (CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Add access rights for the specified identity.
		/// </summary>
		/// <remarks>
		/// Adds the given access rights for the specified identity.
		/// </remarks>
		/// <param name="name">The identity name.</param>
		/// <param name="rights">The access rights.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="name"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="rights"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support the ACL extension.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void AddAccessRights (string name, AccessRights rights, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously add access rights for the specified identity.
		/// </summary>
		/// <remarks>
		/// Asynchronously adds the given access rights for the specified identity.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="name">The identity name.</param>
		/// <param name="rights">The access rights.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="name"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="rights"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support the ACL extension.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task AddAccessRightsAsync (string name, AccessRights rights, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Remove access rights for the specified identity.
		/// </summary>
		/// <remarks>
		/// Removes the given access rights for the specified identity.
		/// </remarks>
		/// <param name="name">The identity name.</param>
		/// <param name="rights">The access rights.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="name"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="rights"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support the ACL extension.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void RemoveAccessRights (string name, AccessRights rights, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously remove access rights for the specified identity.
		/// </summary>
		/// <remarks>
		/// Asynchronously removes the given access rights for the specified identity.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="name">The identity name.</param>
		/// <param name="rights">The access rights.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="name"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="rights"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support the ACL extension.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task RemoveAccessRightsAsync (string name, AccessRights rights, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Set the access rights for the specified identity.
		/// </summary>
		/// <remarks>
		/// Sets the access rights for the specified identity.
		/// </remarks>
		/// <param name="name">The identity name.</param>
		/// <param name="rights">The access rights.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="name"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="rights"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support the ACL extension.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void SetAccessRights (string name, AccessRights rights, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously set the access rights for the specified identity.
		/// </summary>
		/// <remarks>
		/// Asynchronously sets the access rights for the specified identity.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="name">The identity name.</param>
		/// <param name="rights">The access rights.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="name"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="rights"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support the ACL extension.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task SetAccessRightsAsync (string name, AccessRights rights, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Remove all access rights for the given identity.
		/// </summary>
		/// <remarks>
		/// Removes all access rights for the given identity.
		/// </remarks>
		/// <param name="name">The identity name.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="name"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support the ACL extension.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void RemoveAccess (string name, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously remove all access rights for the given identity.
		/// </summary>
		/// <remarks>
		/// Asynchronously removes all access rights for the given identity.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="name">The identity name.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="name"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support the ACL extension.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task RemoveAccessAsync (string name, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Get the quota information for the folder.
		/// </summary>
		/// <remarks>
		/// <para>Gets the quota information for the folder.</para>
		/// <para>To determine if a quotas are supported, check the 
		/// <see cref="IMailStore.SupportsQuotas"/> property.</para>
		/// </remarks>
		/// <returns>The folder quota.</returns>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support quotas.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract FolderQuota GetQuota (CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously get the quota information for the folder.
		/// </summary>
		/// <remarks>
		/// <para>Asynchronously gets the quota information for the folder.</para>
		/// <para>To determine if a quotas are supported, check the 
		/// <see cref="IMailStore.SupportsQuotas"/> property.</para>
		/// </remarks>
		/// <returns>The folder quota.</returns>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support quotas.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<FolderQuota> GetQuotaAsync (CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Set the quota limits for the folder.
		/// </summary>
		/// <remarks>
		/// <para>Sets the quota limits for the folder.</para>
		/// <para>To determine if a quotas are supported, check the 
		/// <see cref="IMailStore.SupportsQuotas"/> property.</para>
		/// </remarks>
		/// <returns>The updated folder quota.</returns>
		/// <param name="messageLimit">If not <c>null</c>, sets the maximum number of messages to allow.</param>
		/// <param name="storageLimit">If not <c>null</c>, sets the maximum storage size (in kilobytes).</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support quotas.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract FolderQuota SetQuota (uint? messageLimit, uint? storageLimit, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously set the quota limits for the folder.
		/// </summary>
		/// <remarks>
		/// <para>Asynchronously sets the quota limits for the folder.</para>
		/// <para>To determine if a quotas are supported, check the 
		/// <see cref="IMailStore.SupportsQuotas"/> property.</para>
		/// </remarks>
		/// <returns>The updated folder quota.</returns>
		/// <param name="messageLimit">If not <c>null</c>, sets the maximum number of messages to allow.</param>
		/// <param name="storageLimit">If not <c>null</c>, sets the maximum storage size (in kilobytes).</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support quotas.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<FolderQuota> SetQuotaAsync (uint? messageLimit, uint? storageLimit, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Get the specified metadata.
		/// </summary>
		/// <remarks>
		/// Gets the specified metadata.
		/// </remarks>
		/// <returns>The requested metadata value.</returns>
		/// <param name="tag">The metadata tag.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The folder does not support metadata.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract string GetMetadata (MetadataTag tag, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously gets the specified metadata.
		/// </summary>
		/// <remarks>
		/// Asynchronously gets the specified metadata.
		/// </remarks>
		/// <returns>The requested metadata value.</returns>
		/// <param name="tag">The metadata tag.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The folder does not support metadata.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<string> GetMetadataAsync (MetadataTag tag, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Get the specified metadata.
		/// </summary>
		/// <remarks>
		/// Gets the specified metadata.
		/// </remarks>
		/// <returns>The requested metadata.</returns>
		/// <param name="tags">The metadata tags.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="tags"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The folder does not support metadata.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public MetadataCollection GetMetadata (IEnumerable<MetadataTag> tags, CancellationToken cancellationToken = default (CancellationToken))
		{
			return GetMetadata (new MetadataOptions (), tags, cancellationToken);
		}

		/// <summary>
		/// Asynchronously gets the specified metadata.
		/// </summary>
		/// <remarks>
		/// Asynchronously gets the specified metadata.
		/// </remarks>
		/// <returns>The requested metadata.</returns>
		/// <param name="tags">The metadata tags.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="tags"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The folder does not support metadata.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task<MetadataCollection> GetMetadataAsync (IEnumerable<MetadataTag> tags, CancellationToken cancellationToken = default (CancellationToken))
		{
			return GetMetadataAsync (new MetadataOptions (), tags, cancellationToken);
		}

		/// <summary>
		/// Get the specified metadata.
		/// </summary>
		/// <remarks>
		/// Gets the specified metadata.
		/// </remarks>
		/// <returns>The requested metadata.</returns>
		/// <param name="options">The metadata options.</param>
		/// <param name="tags">The metadata tags.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="options"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="tags"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The folder does not support metadata.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract MetadataCollection GetMetadata (MetadataOptions options, IEnumerable<MetadataTag> tags, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously gets the specified metadata.
		/// </summary>
		/// <remarks>
		/// Asynchronously gets the specified metadata.
		/// </remarks>
		/// <returns>The requested metadata.</returns>
		/// <param name="options">The metadata options.</param>
		/// <param name="tags">The metadata tags.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="options"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="tags"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The folder does not support metadata.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<MetadataCollection> GetMetadataAsync (MetadataOptions options, IEnumerable<MetadataTag> tags, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Sets the specified metadata.
		/// </summary>
		/// <remarks>
		/// Sets the specified metadata.
		/// </remarks>
		/// <param name="metadata">The metadata.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="metadata"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The folder does not support metadata.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void SetMetadata (MetadataCollection metadata, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously sets the specified metadata.
		/// </summary>
		/// <remarks>
		/// Asynchronously sets the specified metadata.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="metadata">The metadata.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="metadata"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The folder does not support metadata.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task SetMetadataAsync (MetadataCollection metadata, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Expunge the folder, permanently removing all messages marked for deletion.
		/// </summary>
		/// <remarks>
		/// <para>Expunges the folder, permanently removing all messages marked for deletion.</para>
		/// <note type="note">Normally, an <see cref="MessageExpunged"/> event will be emitted for
		/// each message that is expunged. However, if the mail store supports the quick
		/// resynchronization feature and it has been enabled via the
		/// <see cref="MailStore.EnableQuickResync(CancellationToken)"/> method, then
		/// the <see cref="MessagesVanished"/> event will be emitted rather than the
		/// <see cref="MessageExpunged"/> event.</note>
		/// </remarks>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void Expunge (CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously expunge the folder, permanently removing all messages marked for deletion.
		/// </summary>
		/// <remarks>
		/// <para>Asynchronously expunges the folder, permanently removing all messages marked for deletion.</para>
		/// <note type="note">Normally, an <see cref="MessageExpunged"/> event will be emitted for
		/// each message that is expunged. However, if the mail store supports the quick
		/// resynchronization feature and it has been enabled via the
		/// <see cref="MailStore.EnableQuickResync(CancellationToken)"/> method, then
		/// the <see cref="MessagesVanished"/> event will be emitted rather than the
		/// <see cref="MessageExpunged"/> event.</note>
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task ExpungeAsync (CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Expunge the specified uids, permanently removing them from the folder.
		/// </summary>
		/// <remarks>
		/// <para>Expunges the specified uids, permanently removing them from the folder.</para>
		/// <note type="note">Normally, an <see cref="MessageExpunged"/> event will be emitted for
		/// each message that is expunged. However, if the mail store supports the quick
		/// resynchronization feature and it has been enabled via the
		/// <see cref="MailStore.EnableQuickResync(CancellationToken)"/> method, then
		/// the <see cref="MessagesVanished"/> event will be emitted rather than the
		/// <see cref="MessageExpunged"/> event.</note>
		/// </remarks>
		/// <param name="uids">The message uids.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="uids"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void Expunge (IList<UniqueId> uids, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously expunge the specified uids, permanently removing them from the folder.
		/// </summary>
		/// <remarks>
		/// <para>Asynchronously expunges the specified uids, permanently removing them from the folder.</para>
		/// <note type="note">Normally, an <see cref="MessageExpunged"/> event will be emitted for
		/// each message that is expunged. However, if the mail store supports the quick
		/// resynchronization feature and it has been enabled via the
		/// <see cref="MailStore.EnableQuickResync(CancellationToken)"/> method, then
		/// the <see cref="MessagesVanished"/> event will be emitted rather than the
		/// <see cref="MessageExpunged"/> event.</note>
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="uids">The message uids.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="uids"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task ExpungeAsync (IList<UniqueId> uids, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Append the specified message to the folder.
		/// </summary>
		/// <remarks>
		/// Appends the specified message to the folder and returns the UniqueId assigned to the message.
		/// </remarks>
		/// <returns>The UID of the appended message, if available; otherwise, <c>null</c>.</returns>
		/// <param name="message">The message.</param>
		/// <param name="flags">The message flags.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="message"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual UniqueId? Append (MimeMessage message, MessageFlags flags = MessageFlags.None, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null)
		{
			return Append (FormatOptions.Default, message, flags, cancellationToken, progress);
		}

		/// <summary>
		/// Asynchronously append the specified message to the folder.
		/// </summary>
		/// <remarks>
		/// Asynchronously appends the specified message to the folder and returns the UniqueId assigned to the message.
		/// </remarks>
		/// <returns>The UID of the appended message, if available; otherwise, <c>null</c>.</returns>
		/// <param name="message">The message.</param>
		/// <param name="flags">The message flags.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="message"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task<UniqueId?> AppendAsync (MimeMessage message, MessageFlags flags = MessageFlags.None, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null)
		{
			return AppendAsync (FormatOptions.Default, message, flags, cancellationToken, progress);
		}

		/// <summary>
		/// Append the specified message to the folder.
		/// </summary>
		/// <remarks>
		/// Appends the specified message to the folder and returns the UniqueId assigned to the message.
		/// </remarks>
		/// <returns>The UID of the appended message, if available; otherwise, <c>null</c>.</returns>
		/// <param name="message">The message.</param>
		/// <param name="flags">The message flags.</param>
		/// <param name="date">The received date of the message.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="message"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual UniqueId? Append (MimeMessage message, MessageFlags flags, DateTimeOffset date, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null)
		{
			return Append (FormatOptions.Default, message, flags, date, cancellationToken, progress);
		}

		/// <summary>
		/// Asynchronously append the specified message to the folder.
		/// </summary>
		/// <remarks>
		/// Asynchronously appends the specified message to the folder and returns the UniqueId assigned to the message.
		/// </remarks>
		/// <returns>The UID of the appended message, if available; otherwise, <c>null</c>.</returns>
		/// <param name="message">The message.</param>
		/// <param name="flags">The message flags.</param>
		/// <param name="date">The received date of the message.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="message"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task<UniqueId?> AppendAsync (MimeMessage message, MessageFlags flags, DateTimeOffset date, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null)
		{
			return AppendAsync (FormatOptions.Default, message, flags, date, cancellationToken, progress);
		}

		/// <summary>
		/// Append the specified message to the folder.
		/// </summary>
		/// <remarks>
		/// Appends the specified message to the folder and returns the UniqueId assigned to the message.
		/// </remarks>
		/// <returns>The UID of the appended message, if available; otherwise, <c>null</c>.</returns>
		/// <param name="message">The message.</param>
		/// <param name="flags">The message flags.</param>
		/// <param name="date">The received date of the message.</param>
		/// <param name="annotations">The message annotations.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="message"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// One or more <paramref name="annotations"/> does not define any properties.
		/// </exception>"
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual UniqueId? Append (MimeMessage message, MessageFlags flags, DateTimeOffset? date, IList<Annotation> annotations, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null)
		{
			return Append (FormatOptions.Default, message, flags, date, annotations, cancellationToken, progress);
		}

		/// <summary>
		/// Asynchronously append the specified message to the folder.
		/// </summary>
		/// <remarks>
		/// Asynchronously appends the specified message to the folder and returns the UniqueId assigned to the message.
		/// </remarks>
		/// <returns>The UID of the appended message, if available; otherwise, <c>null</c>.</returns>
		/// <param name="message">The message.</param>
		/// <param name="flags">The message flags.</param>
		/// <param name="date">The received date of the message.</param>
		/// <param name="annotations">The message annotations.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="message"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// One or more <paramref name="annotations"/> does not define any properties.
		/// </exception>"
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task<UniqueId?> AppendAsync (MimeMessage message, MessageFlags flags, DateTimeOffset? date, IList<Annotation> annotations, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null)
		{
			return AppendAsync (FormatOptions.Default, message, flags, date, annotations, cancellationToken, progress);
		}

		/// <summary>
		/// Append the specified message to the folder.
		/// </summary>
		/// <remarks>
		/// Appends the specified message to the folder and returns the UniqueId assigned to the message.
		/// </remarks>
		/// <returns>The UID of the appended message, if available; otherwise, <c>null</c>.</returns>
		/// <param name="options">The formatting options.</param>
		/// <param name="message">The message.</param>
		/// <param name="flags">The message flags.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="options"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="message"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Internationalized formatting was requested but has not been enabled.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// Internationalized formatting was requested but is not supported by the server.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract UniqueId? Append (FormatOptions options, MimeMessage message, MessageFlags flags = MessageFlags.None, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Asynchronously append the specified message to the folder.
		/// </summary>
		/// <remarks>
		/// Asynchronously appends the specified message to the folder and returns the UniqueId assigned to the message.
		/// </remarks>
		/// <returns>The UID of the appended message, if available; otherwise, <c>null</c>.</returns>
		/// <param name="options">The formatting options.</param>
		/// <param name="message">The message.</param>
		/// <param name="flags">The message flags.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="options"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="message"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Internationalized formatting was requested but has not been enabled.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// Internationalized formatting was requested but is not supported by the server.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<UniqueId?> AppendAsync (FormatOptions options, MimeMessage message, MessageFlags flags = MessageFlags.None, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Append the specified message to the folder.
		/// </summary>
		/// <remarks>
		/// Appends the specified message to the folder and returns the UniqueId assigned to the message.
		/// </remarks>
		/// <returns>The UID of the appended message, if available; otherwise, <c>null</c>.</returns>
		/// <param name="options">The formatting options.</param>
		/// <param name="message">The message.</param>
		/// <param name="flags">The message flags.</param>
		/// <param name="date">The received date of the message.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="options"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="message"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Internationalized formatting was requested but has not been enabled.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// Internationalized formatting was requested but is not supported by the server.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract UniqueId? Append (FormatOptions options, MimeMessage message, MessageFlags flags, DateTimeOffset date, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Asynchronously append the specified message to the folder.
		/// </summary>
		/// <remarks>
		/// Asynchronously appends the specified message to the folder and returns the UniqueId assigned to the message.
		/// </remarks>
		/// <returns>The UID of the appended message, if available; otherwise, <c>null</c>.</returns>
		/// <param name="options">The formatting options.</param>
		/// <param name="message">The message.</param>
		/// <param name="flags">The message flags.</param>
		/// <param name="date">The received date of the message.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="options"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="message"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Internationalized formatting was requested but has not been enabled.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// Internationalized formatting was requested but is not supported by the server.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<UniqueId?> AppendAsync (FormatOptions options, MimeMessage message, MessageFlags flags, DateTimeOffset date, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Append the specified message to the folder.
		/// </summary>
		/// <remarks>
		/// Appends the specified message to the folder and returns the UniqueId assigned to the message.
		/// </remarks>
		/// <returns>The UID of the appended message, if available; otherwise, <c>null</c>.</returns>
		/// <param name="options">The formatting options.</param>
		/// <param name="message">The message.</param>
		/// <param name="flags">The message flags.</param>
		/// <param name="date">The received date of the message.</param>
		/// <param name="annotations">The message annotations.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="options"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="message"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Internationalized formatting was requested but has not been enabled.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// Internationalized formatting was requested but is not supported by the server.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract UniqueId? Append (FormatOptions options, MimeMessage message, MessageFlags flags, DateTimeOffset? date, IList<Annotation> annotations, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Asynchronously append the specified message to the folder.
		/// </summary>
		/// <remarks>
		/// Asynchronously appends the specified message to the folder and returns the UniqueId assigned to the message.
		/// </remarks>
		/// <returns>The UID of the appended message, if available; otherwise, <c>null</c>.</returns>
		/// <param name="options">The formatting options.</param>
		/// <param name="message">The message.</param>
		/// <param name="flags">The message flags.</param>
		/// <param name="date">The received date of the message.</param>
		/// <param name="annotations">The message annotations.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="options"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="message"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Internationalized formatting was requested but has not been enabled.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// Internationalized formatting was requested but is not supported by the server.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<UniqueId?> AppendAsync (FormatOptions options, MimeMessage message, MessageFlags flags, DateTimeOffset? date, IList<Annotation> annotations, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Append the specified messages to the folder.
		/// </summary>
		/// <remarks>
		/// Appends the specified messages to the folder and returns the UniqueIds assigned to the messages.
		/// </remarks>
		/// <returns>The UIDs of the appended messages, if available; otherwise an empty array.</returns>
		/// <param name="messages">The array of messages to append to the folder.</param>
		/// <param name="flags">The message flags to use for each message.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="messages"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="flags"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="messages"/> is null.</para>
		/// <para>-or-</para>
		/// <para>The number of messages does not match the number of flags.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual IList<UniqueId> Append (IList<MimeMessage> messages, IList<MessageFlags> flags, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null)
		{
			return Append (FormatOptions.Default, messages, flags, cancellationToken, progress);
		}

		/// <summary>
		/// Asynchronously append the specified messages to the folder.
		/// </summary>
		/// <remarks>
		/// Asynchronously appends the specified messages to the folder and returns the UniqueIds assigned to the messages.
		/// </remarks>
		/// <returns>The UIDs of the appended messages, if available; otherwise an empty array.</returns>
		/// <param name="messages">The array of messages to append to the folder.</param>
		/// <param name="flags">The message flags to use for each message.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="messages"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="flags"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="messages"/> is null.</para>
		/// <para>-or-</para>
		/// <para>The number of messages does not match the number of flags.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task<IList<UniqueId>> AppendAsync (IList<MimeMessage> messages, IList<MessageFlags> flags, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null)
		{
			return AppendAsync (FormatOptions.Default, messages, flags, cancellationToken, progress);
		}

		/// <summary>
		/// Append the specified messages to the folder.
		/// </summary>
		/// <remarks>
		/// Appends the specified messages to the folder and returns the UniqueIds assigned to the messages.
		/// </remarks>
		/// <returns>The UIDs of the appended messages, if available; otherwise an empty array.</returns>
		/// <param name="messages">The array of messages to append to the folder.</param>
		/// <param name="flags">The message flags to use for each of the messages.</param>
		/// <param name="dates">The received dates to use for each of the messages.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="messages"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="flags"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="dates"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="messages"/> is null.</para>
		/// <para>-or-</para>
		/// <para>The number of messages, flags, and dates do not match.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual IList<UniqueId> Append (IList<MimeMessage> messages, IList<MessageFlags> flags, IList<DateTimeOffset> dates, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null)
		{
			return Append (FormatOptions.Default, messages, flags, dates, cancellationToken, progress);
		}

		/// <summary>
		/// Asynchronously append the specified messages to the folder.
		/// </summary>
		/// <remarks>
		/// Asynchronously appends the specified messages to the folder and returns the UniqueIds assigned to the messages.
		/// </remarks>
		/// <returns>The UIDs of the appended messages, if available; otherwise an empty array.</returns>
		/// <param name="messages">The array of messages to append to the folder.</param>
		/// <param name="flags">The message flags to use for each of the messages.</param>
		/// <param name="dates">The received dates to use for each of the messages.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="messages"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="flags"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="dates"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="messages"/> is null.</para>
		/// <para>-or-</para>
		/// <para>The number of messages, flags, and dates do not match.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task<IList<UniqueId>> AppendAsync (IList<MimeMessage> messages, IList<MessageFlags> flags, IList<DateTimeOffset> dates, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null)
		{
			return AppendAsync (FormatOptions.Default, messages, flags, dates, cancellationToken, progress);
		}

		/// <summary>
		/// Append the specified messages to the folder.
		/// </summary>
		/// <remarks>
		/// Appends the specified messages to the folder and returns the UniqueIds assigned to the messages.
		/// </remarks>
		/// <returns>The UIDs of the appended messages, if available; otherwise an empty array.</returns>
		/// <param name="options">The formatting options.</param>
		/// <param name="messages">The array of messages to append to the folder.</param>
		/// <param name="flags">The message flags to use for each message.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="options"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="messages"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="flags"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="messages"/> is null.</para>
		/// <para>-or-</para>
		/// <para>The number of messages does not match the number of flags.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Internationalized formatting was requested but has not been enabled.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// Internationalized formatting was requested but is not supported by the server.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<UniqueId> Append (FormatOptions options, IList<MimeMessage> messages, IList<MessageFlags> flags, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Asynchronously append the specified messages to the folder.
		/// </summary>
		/// <remarks>
		/// Asynchronously appends the specified messages to the folder and returns the UniqueIds assigned to the messages.
		/// </remarks>
		/// <returns>The UIDs of the appended messages, if available; otherwise an empty array.</returns>
		/// <param name="options">The formatting options.</param>
		/// <param name="messages">The array of messages to append to the folder.</param>
		/// <param name="flags">The message flags to use for each message.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="options"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="messages"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="flags"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="messages"/> is null.</para>
		/// <para>-or-</para>
		/// <para>The number of messages does not match the number of flags.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Internationalized formatting was requested but has not been enabled.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// Internationalized formatting was requested but is not supported by the server.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<UniqueId>> AppendAsync (FormatOptions options, IList<MimeMessage> messages, IList<MessageFlags> flags, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Append the specified messages to the folder.
		/// </summary>
		/// <remarks>
		/// Appends the specified messages to the folder and returns the UniqueIds assigned to the messages.
		/// </remarks>
		/// <returns>The UIDs of the appended messages, if available; otherwise an empty array.</returns>
		/// <param name="options">The formatting options.</param>
		/// <param name="messages">The array of messages to append to the folder.</param>
		/// <param name="flags">The message flags to use for each of the messages.</param>
		/// <param name="dates">The received dates to use for each of the messages.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="options"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="messages"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="flags"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="dates"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="messages"/> is null.</para>
		/// <para>-or-</para>
		/// <para>The number of messages, flags, and dates do not match.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Internationalized formatting was requested but has not been enabled.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// Internationalized formatting was requested but is not supported by the server.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<UniqueId> Append (FormatOptions options, IList<MimeMessage> messages, IList<MessageFlags> flags, IList<DateTimeOffset> dates, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Asynchronously append the specified messages to the folder.
		/// </summary>
		/// <remarks>
		/// Asynchronously appends the specified messages to the folder and returns the UniqueIds assigned to the messages.
		/// </remarks>
		/// <returns>The UIDs of the appended messages, if available; otherwise an empty array.</returns>
		/// <param name="options">The formatting options.</param>
		/// <param name="messages">The array of messages to append to the folder.</param>
		/// <param name="flags">The message flags to use for each of the messages.</param>
		/// <param name="dates">The received dates to use for each of the messages.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="options"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="messages"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="flags"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="dates"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="messages"/> is null.</para>
		/// <para>-or-</para>
		/// <para>The number of messages, flags, and dates do not match.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Internationalized formatting was requested but has not been enabled.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// Internationalized formatting was requested but is not supported by the server.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<UniqueId>> AppendAsync (FormatOptions options, IList<MimeMessage> messages, IList<MessageFlags> flags, IList<DateTimeOffset> dates, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Replace a message in the folder.
		/// </summary>
		/// <remarks>
		/// Replaces the specified message in the folder and returns the UniqueId assigned to the new message.
		/// </remarks>
		/// <returns>The UID of the new message, if available; otherwise, <c>null</c>.</returns>
		/// <param name="uid">The UID of the message to be replaced.</param>
		/// <param name="message">The message.</param>
		/// <param name="flags">The message flags.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="message"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Internationalized formatting was requested but has not been enabled.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="MailFolder"/> is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The server replied with a NO or BAD response.
		/// </exception>
		public virtual UniqueId? Replace (UniqueId uid, MimeMessage message, MessageFlags flags = MessageFlags.None, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null)
		{
			return Replace (FormatOptions.Default, uid, message, flags, cancellationToken, progress);
		}

		/// <summary>
		/// Asynchronously replace a message in the folder.
		/// </summary>
		/// <remarks>
		/// Replaces the specified message in the folder and returns the UniqueId assigned to the new message.
		/// </remarks>
		/// <returns>The UID of the new message, if available; otherwise, <c>null</c>.</returns>
		/// <param name="uid">The UID of the message to be replaced.</param>
		/// <param name="message">The message.</param>
		/// <param name="flags">The message flags.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="message"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Internationalized formatting was requested but has not been enabled.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="MailFolder"/> is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The server replied with a NO or BAD response.
		/// </exception>
		public virtual Task<UniqueId?> ReplaceAsync (UniqueId uid, MimeMessage message, MessageFlags flags = MessageFlags.None, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null)
		{
			return ReplaceAsync (FormatOptions.Default, uid, message, flags, cancellationToken, progress);
		}

		/// <summary>
		/// Replace a message in the folder.
		/// </summary>
		/// <remarks>
		/// Replaces the specified message in the folder and returns the UniqueId assigned to the new message.
		/// </remarks>
		/// <returns>The UID of the new message, if available; otherwise, <c>null</c>.</returns>
		/// <param name="uid">The UID of the message to be replaced.</param>
		/// <param name="message">The message.</param>
		/// <param name="flags">The message flags.</param>
		/// <param name="date">The received date of the message.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="message"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="MailFolder"/> is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The server replied with a NO or BAD response.
		/// </exception>
		public virtual UniqueId? Replace (UniqueId uid, MimeMessage message, MessageFlags flags, DateTimeOffset date, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null)
		{
			return Replace (FormatOptions.Default, uid, message, flags, date, cancellationToken, progress);
		}

		/// <summary>
		/// Asynchronously replace a message in the folder.
		/// </summary>
		/// <remarks>
		/// Replaces the specified message in the folder and returns the UniqueId assigned to the new message.
		/// </remarks>
		/// <returns>The UID of the new message, if available; otherwise, <c>null</c>.</returns>
		/// <param name="uid">The UID of the message to be replaced.</param>
		/// <param name="message">The message.</param>
		/// <param name="flags">The message flags.</param>
		/// <param name="date">The received date of the message.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="message"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="MailFolder"/> is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The server replied with a NO or BAD response.
		/// </exception>
		public virtual Task<UniqueId?> ReplaceAsync (UniqueId uid, MimeMessage message, MessageFlags flags, DateTimeOffset date, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null)
		{
			return ReplaceAsync (FormatOptions.Default, uid, message, flags, date, cancellationToken, progress);
		}

		/// <summary>
		/// Replace a message in the folder.
		/// </summary>
		/// <remarks>
		/// Replaces the specified message in the folder and returns the UniqueId assigned to the new message.
		/// </remarks>
		/// <returns>The UID of the new message, if available; otherwise, <c>null</c>.</returns>
		/// <param name="options">The formatting options.</param>
		/// <param name="uid">The UID of the message to be replaced.</param>
		/// <param name="message">The message.</param>
		/// <param name="flags">The message flags.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="options"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="message"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Internationalized formatting was requested but has not been enabled.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="MailFolder"/> is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// <para>Internationalized formatting was requested but is not supported by the server.</para>
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The server replied with a NO or BAD response.
		/// </exception>
		public abstract UniqueId? Replace (FormatOptions options, UniqueId uid, MimeMessage message, MessageFlags flags = MessageFlags.None, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Asynchronously replace a message in the folder.
		/// </summary>
		/// <remarks>
		/// Replaces the specified message in the folder and returns the UniqueId assigned to the new message.
		/// </remarks>
		/// <returns>The UID of the new message, if available; otherwise, <c>null</c>.</returns>
		/// <param name="options">The formatting options.</param>
		/// <param name="uid">The UID of the message to be replaced.</param>
		/// <param name="message">The message.</param>
		/// <param name="flags">The message flags.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="options"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="message"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Internationalized formatting was requested but has not been enabled.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="MailFolder"/> is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// <para>Internationalized formatting was requested but is not supported by the server.</para>
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The server replied with a NO or BAD response.
		/// </exception>
		public abstract Task<UniqueId?> ReplaceAsync (FormatOptions options, UniqueId uid, MimeMessage message, MessageFlags flags = MessageFlags.None, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Replace a message in the folder.
		/// </summary>
		/// <remarks>
		/// Replaces the specified message in the folder and returns the UniqueId assigned to the new message.
		/// </remarks>
		/// <returns>The UID of the new message, if available; otherwise, <c>null</c>.</returns>
		/// <param name="options">The formatting options.</param>
		/// <param name="uid">The UID of the message to be replaced.</param>
		/// <param name="message">The message.</param>
		/// <param name="flags">The message flags.</param>
		/// <param name="date">The received date of the message.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="options"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="message"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Internationalized formatting was requested but has not been enabled.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="MailFolder"/> is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// <para>Internationalized formatting was requested but is not supported by the server.</para>
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The server replied with a NO or BAD response.
		/// </exception>
		public abstract UniqueId? Replace (FormatOptions options, UniqueId uid, MimeMessage message, MessageFlags flags, DateTimeOffset date, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Asynchronously replace a message in the folder.
		/// </summary>
		/// <remarks>
		/// Replaces the specified message in the folder and returns the UniqueId assigned to the new message.
		/// </remarks>
		/// <returns>The UID of the new message, if available; otherwise, <c>null</c>.</returns>
		/// <param name="options">The formatting options.</param>
		/// <param name="uid">The UID of the message to be replaced.</param>
		/// <param name="message">The message.</param>
		/// <param name="flags">The message flags.</param>
		/// <param name="date">The received date of the message.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="options"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="message"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Internationalized formatting was requested but has not been enabled.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="MailFolder"/> is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// <para>Internationalized formatting was requested but is not supported by the server.</para>
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The server replied with a NO or BAD response.
		/// </exception>
		public abstract Task<UniqueId?> ReplaceAsync (FormatOptions options, UniqueId uid, MimeMessage message, MessageFlags flags, DateTimeOffset date, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Replace a message in the folder.
		/// </summary>
		/// <remarks>
		/// Replaces the specified message in the folder and returns the UniqueId assigned to the new message.
		/// </remarks>
		/// <returns>The UID of the new message, if available; otherwise, <c>null</c>.</returns>
		/// <param name="index">The index of the message to be replaced.</param>
		/// <param name="message">The message.</param>
		/// <param name="flags">The message flags.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="message"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="index"/> is out of range.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Internationalized formatting was requested but has not been enabled.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="MailFolder"/> is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The server replied with a NO or BAD response.
		/// </exception>
		public virtual UniqueId? Replace (int index, MimeMessage message, MessageFlags flags = MessageFlags.None, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null)
		{
			return Replace (FormatOptions.Default, index, message, flags, cancellationToken, progress);
		}

		/// <summary>
		/// Asynchronously replace a message in the folder.
		/// </summary>
		/// <remarks>
		/// Replaces the specified message in the folder and returns the UniqueId assigned to the new message.
		/// </remarks>
		/// <returns>The UID of the new message, if available; otherwise, <c>null</c>.</returns>
		/// <param name="index">The index of the message to be replaced.</param>
		/// <param name="message">The message.</param>
		/// <param name="flags">The message flags.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="message"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="index"/> is out of range.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Internationalized formatting was requested but has not been enabled.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="MailFolder"/> is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The server replied with a NO or BAD response.
		/// </exception>
		public virtual Task<UniqueId?> ReplaceAsync (int index, MimeMessage message, MessageFlags flags = MessageFlags.None, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null)
		{
			return ReplaceAsync (FormatOptions.Default, index, message, flags, cancellationToken, progress);
		}

		/// <summary>
		/// Replace a message in the folder.
		/// </summary>
		/// <remarks>
		/// Replaces the specified message in the folder and returns the UniqueId assigned to the new message.
		/// </remarks>
		/// <returns>The UID of the new message, if available; otherwise, <c>null</c>.</returns>
		/// <param name="index">The index of the message to be replaced.</param>
		/// <param name="message">The message.</param>
		/// <param name="flags">The message flags.</param>
		/// <param name="date">The received date of the message.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="message"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="index"/> is out of range.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="MailFolder"/> is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The server replied with a NO or BAD response.
		/// </exception>
		public virtual UniqueId? Replace (int index, MimeMessage message, MessageFlags flags, DateTimeOffset date, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null)
		{
			return Replace (FormatOptions.Default, index, message, flags, date, cancellationToken, progress);
		}

		/// <summary>
		/// Asynchronously replace a message in the folder.
		/// </summary>
		/// <remarks>
		/// Replaces the specified message in the folder and returns the UniqueId assigned to the new message.
		/// </remarks>
		/// <returns>The UID of the new message, if available; otherwise, <c>null</c>.</returns>
		/// <param name="index">The index of the message to be replaced.</param>
		/// <param name="message">The message.</param>
		/// <param name="flags">The message flags.</param>
		/// <param name="date">The received date of the message.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="message"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="index"/> is out of range.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="MailFolder"/> is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The server replied with a NO or BAD response.
		/// </exception>
		public virtual Task<UniqueId?> ReplaceAsync (int index, MimeMessage message, MessageFlags flags, DateTimeOffset date, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null)
		{
			return ReplaceAsync (FormatOptions.Default, index, message, flags, date, cancellationToken, progress);
		}

		/// <summary>
		/// Replace a message in the folder.
		/// </summary>
		/// <remarks>
		/// Replaces the specified message in the folder and returns the UniqueId assigned to the new message.
		/// </remarks>
		/// <returns>The UID of the new message, if available; otherwise, <c>null</c>.</returns>
		/// <param name="options">The formatting options.</param>
		/// <param name="index">The index of the message to be replaced.</param>
		/// <param name="message">The message.</param>
		/// <param name="flags">The message flags.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="options"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="message"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="index"/> is out of range.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Internationalized formatting was requested but has not been enabled.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="MailFolder"/> is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// <para>Internationalized formatting was requested but is not supported by the server.</para>
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The server replied with a NO or BAD response.
		/// </exception>
		public abstract UniqueId? Replace (FormatOptions options, int index, MimeMessage message, MessageFlags flags = MessageFlags.None, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Asynchronously replace a message in the folder.
		/// </summary>
		/// <remarks>
		/// Replaces the specified message in the folder and returns the UniqueId assigned to the new message.
		/// </remarks>
		/// <returns>The UID of the new message, if available; otherwise, <c>null</c>.</returns>
		/// <param name="options">The formatting options.</param>
		/// <param name="index">The index of the message to be replaced.</param>
		/// <param name="message">The message.</param>
		/// <param name="flags">The message flags.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="options"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="message"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="index"/> is out of range.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Internationalized formatting was requested but has not been enabled.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="MailFolder"/> is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// <para>Internationalized formatting was requested but is not supported by the server.</para>
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The server replied with a NO or BAD response.
		/// </exception>
		public abstract Task<UniqueId?> ReplaceAsync (FormatOptions options, int index, MimeMessage message, MessageFlags flags = MessageFlags.None, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Replace a message in the folder.
		/// </summary>
		/// <remarks>
		/// Replaces the specified message in the folder and returns the UniqueId assigned to the new message.
		/// </remarks>
		/// <returns>The UID of the new message, if available; otherwise, <c>null</c>.</returns>
		/// <param name="options">The formatting options.</param>
		/// <param name="index">The index of the message to be replaced.</param>
		/// <param name="message">The message.</param>
		/// <param name="flags">The message flags.</param>
		/// <param name="date">The received date of the message.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="options"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="message"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="index"/> is out of range.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Internationalized formatting was requested but has not been enabled.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="MailFolder"/> is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// <para>Internationalized formatting was requested but is not supported by the server.</para>
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The server replied with a NO or BAD response.
		/// </exception>
		public abstract UniqueId? Replace (FormatOptions options, int index, MimeMessage message, MessageFlags flags, DateTimeOffset date, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Asynchronously replace a message in the folder.
		/// </summary>
		/// <remarks>
		/// Replaces the specified message in the folder and returns the UniqueId assigned to the new message.
		/// </remarks>
		/// <returns>The UID of the new message, if available; otherwise, <c>null</c>.</returns>
		/// <param name="options">The formatting options.</param>
		/// <param name="index">The index of the message to be replaced.</param>
		/// <param name="message">The message.</param>
		/// <param name="flags">The message flags.</param>
		/// <param name="date">The received date of the message.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="options"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="message"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="index"/> is out of range.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Internationalized formatting was requested but has not been enabled.
		/// </exception>
		/// <exception cref="FolderNotFoundException">
		/// The <see cref="MailFolder"/> does not exist.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="MailFolder"/> is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// <para>Internationalized formatting was requested but is not supported by the server.</para>
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The server replied with a NO or BAD response.
		/// </exception>
		public abstract Task<UniqueId?> ReplaceAsync (FormatOptions options, int index, MimeMessage message, MessageFlags flags, DateTimeOffset date, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Copy the specified message to the destination folder.
		/// </summary>
		/// <remarks>
		/// Copies the specified message to the destination folder.
		/// </remarks>
		/// <returns>The UID of the message in the destination folder, if available; otherwise, <c>null</c>.</returns>
		/// <param name="uid">The UID of the message to copy.</param>
		/// <param name="destination">The destination folder.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="destination"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="uid"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>The destination folder does not belong to the <see cref="IMailStore"/>.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support the UIDPLUS extension.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual UniqueId? CopyTo (UniqueId uid, IMailFolder destination, CancellationToken cancellationToken = default (CancellationToken))
		{
			if (destination == null)
				throw new ArgumentNullException (nameof (destination));

			var uids = CopyTo (new [] { uid }, destination, cancellationToken);

			if (uids != null && uids.Destination.Count > 0)
				return uids.Destination[0];

			return null;
		}

		/// <summary>
		/// Asynchronously copy the specified message to the destination folder.
		/// </summary>
		/// <remarks>
		/// Asynchronously copies the specified message to the destination folder.
		/// </remarks>
		/// <returns>The UID of the message in the destination folder, if available; otherwise, <c>null</c>.</returns>
		/// <param name="uid">The UID of the message to copy.</param>
		/// <param name="destination">The destination folder.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="destination"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="uid"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>The destination folder does not belong to the <see cref="IMailStore"/>.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support the UIDPLUS extension.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual async Task<UniqueId?> CopyToAsync (UniqueId uid, IMailFolder destination, CancellationToken cancellationToken = default (CancellationToken))
		{
			if (destination == null)
				throw new ArgumentNullException (nameof (destination));

			var uids = await CopyToAsync (new [] { uid }, destination, cancellationToken).ConfigureAwait (false);

			if (uids != null && uids.Destination.Count > 0)
				return uids.Destination[0];

			return null;
		}

		/// <summary>
		/// Copy the specified messages to the destination folder.
		/// </summary>
		/// <remarks>
		/// Copies the specified messages to the destination folder.
		/// </remarks>
		/// <returns>The UID mapping of the messages in the destination folder, if available; otherwise an empty mapping.</returns>
		/// <param name="uids">The UIDs of the messages to copy.</param>
		/// <param name="destination">The destination folder.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="destination"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>The destination folder does not belong to the <see cref="IMailStore"/>.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support the UIDPLUS extension.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract UniqueIdMap CopyTo (IList<UniqueId> uids, IMailFolder destination, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously copy the specified messages to the destination folder.
		/// </summary>
		/// <remarks>
		/// Asynchronously copies the specified messages to the destination folder.
		/// </remarks>
		/// <returns>The UID mapping of the messages in the destination folder, if available; otherwise an empty mapping.</returns>
		/// <param name="uids">The UIDs of the messages to copy.</param>
		/// <param name="destination">The destination folder.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="destination"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>The destination folder does not belong to the <see cref="IMailStore"/>.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support the UIDPLUS extension.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<UniqueIdMap> CopyToAsync (IList<UniqueId> uids, IMailFolder destination, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Move the specified message to the destination folder.
		/// </summary>
		/// <remarks>
		/// Moves the specified message to the destination folder.
		/// </remarks>
		/// <returns>The UID of the message in the destination folder, if available; otherwise, <c>null</c>.</returns>
		/// <param name="uid">The UID of the message to move.</param>
		/// <param name="destination">The destination folder.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="destination"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="uid"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>The destination folder does not belong to the <see cref="IMailStore"/>.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support the UIDPLUS extension.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual UniqueId? MoveTo (UniqueId uid, IMailFolder destination, CancellationToken cancellationToken = default (CancellationToken))
		{
			if (destination == null)
				throw new ArgumentNullException (nameof (destination));

			var uids = MoveTo (new [] { uid }, destination, cancellationToken);

			if (uids != null && uids.Destination.Count > 0)
				return uids.Destination[0];

			return null;
		}

		/// <summary>
		/// Asynchronously move the specified message to the destination folder.
		/// </summary>
		/// <remarks>
		/// Asynchronously moves the specified message to the destination folder.
		/// </remarks>
		/// <returns>The UID of the message in the destination folder, if available; otherwise, <c>null</c>.</returns>
		/// <param name="uid">The UID of the message to move.</param>
		/// <param name="destination">The destination folder.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="destination"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="uid"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>The destination folder does not belong to the <see cref="IMailStore"/>.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support the UIDPLUS extension.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual async Task<UniqueId?> MoveToAsync (UniqueId uid, IMailFolder destination, CancellationToken cancellationToken = default (CancellationToken))
		{
			if (destination == null)
				throw new ArgumentNullException (nameof (destination));

			var uids = await MoveToAsync (new [] { uid }, destination, cancellationToken).ConfigureAwait (false);

			if (uids != null && uids.Destination.Count > 0)
				return uids.Destination[0];

			return null;
		}

		/// <summary>
		/// Move the specified messages to the destination folder.
		/// </summary>
		/// <remarks>
		/// Moves the specified messages to the destination folder.
		/// </remarks>
		/// <returns>The UID mapping of the messages in the destination folder, if available; otherwise an empty mapping.</returns>
		/// <param name="uids">The UIDs of the messages to move.</param>
		/// <param name="destination">The destination folder.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="destination"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>The destination folder does not belong to the <see cref="IMailStore"/>.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support the UIDPLUS extension.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract UniqueIdMap MoveTo (IList<UniqueId> uids, IMailFolder destination, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously move the specified messages to the destination folder.
		/// </summary>
		/// <remarks>
		/// Asynchronously moves the specified messages to the destination folder.
		/// </remarks>
		/// <returns>The UID mapping of the messages in the destination folder, if available; otherwise an empty mapping.</returns>
		/// <param name="uids">The UIDs of the messages to move.</param>
		/// <param name="destination">The destination folder.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="destination"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>The destination folder does not belong to the <see cref="IMailStore"/>.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The mail store does not support the UIDPLUS extension.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<UniqueIdMap> MoveToAsync (IList<UniqueId> uids, IMailFolder destination, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Copy the specified message to the destination folder.
		/// </summary>
		/// <remarks>
		/// Copies the specified message to the destination folder.
		/// </remarks>
		/// <param name="index">The index of the message to copy.</param>
		/// <param name="destination">The destination folder.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="destination"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="index"/> does not refer to a valid message index.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// The destination folder does not belong to the <see cref="IMailStore"/>.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual void CopyTo (int index, IMailFolder destination, CancellationToken cancellationToken = default (CancellationToken))
		{
			if (index < 0 || index >= Count)
				throw new ArgumentOutOfRangeException (nameof (index));

			if (destination == null)
				throw new ArgumentNullException (nameof (destination));

			CopyTo (new [] { index }, destination, cancellationToken);
		}

		/// <summary>
		/// Asynchronously copy the specified message to the destination folder.
		/// </summary>
		/// <remarks>
		/// Asynchronously copies the specified message to the destination folder.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="index">The indexes of the message to copy.</param>
		/// <param name="destination">The destination folder.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="destination"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="index"/> does not refer to a valid message index.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// The destination folder does not belong to the <see cref="IMailStore"/>.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task CopyToAsync (int index, IMailFolder destination, CancellationToken cancellationToken = default (CancellationToken))
		{
			if (index < 0 || index >= Count)
				throw new ArgumentOutOfRangeException (nameof (index));

			if (destination == null)
				throw new ArgumentNullException (nameof (destination));

			return CopyToAsync (new [] { index }, destination, cancellationToken);
		}

		/// <summary>
		/// Copy the specified messages to the destination folder.
		/// </summary>
		/// <remarks>
		/// Copies the specified messages to the destination folder.
		/// </remarks>
		/// <param name="indexes">The indexes of the messages to copy.</param>
		/// <param name="destination">The destination folder.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="indexes"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="destination"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>The destination folder does not belong to the <see cref="IMailStore"/>.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void CopyTo (IList<int> indexes, IMailFolder destination, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously copy the specified messages to the destination folder.
		/// </summary>
		/// <remarks>
		/// Asynchronously copies the specified messages to the destination folder.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="indexes">The indexes of the messages to copy.</param>
		/// <param name="destination">The destination folder.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="indexes"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="destination"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>The destination folder does not belong to the <see cref="IMailStore"/>.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task CopyToAsync (IList<int> indexes, IMailFolder destination, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Move the specified message to the destination folder.
		/// </summary>
		/// <remarks>
		/// Moves the specified message to the destination folder.
		/// </remarks>
		/// <param name="index">The index of the message to move.</param>
		/// <param name="destination">The destination folder.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="destination"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="index"/> does not refer to a valid message index.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// The destination folder does not belong to the <see cref="IMailStore"/>.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual void MoveTo (int index, IMailFolder destination, CancellationToken cancellationToken = default (CancellationToken))
		{
			if (index < 0 || index >= Count)
				throw new ArgumentOutOfRangeException (nameof (index));

			if (destination == null)
				throw new ArgumentNullException (nameof (destination));

			MoveTo (new [] { index }, destination, cancellationToken);
		}

		/// <summary>
		/// Asynchronously move the specified message to the destination folder.
		/// </summary>
		/// <remarks>
		/// Asynchronously moves the specified message to the destination folder.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="index">The index of the message to move.</param>
		/// <param name="destination">The destination folder.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="destination"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="index"/> does not refer to a valid message index.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// The destination folder does not belong to the <see cref="IMailStore"/>.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task MoveToAsync (int index, IMailFolder destination, CancellationToken cancellationToken = default (CancellationToken))
		{
			if (index < 0 || index >= Count)
				throw new ArgumentOutOfRangeException (nameof (index));

			if (destination == null)
				throw new ArgumentNullException (nameof (destination));

			return MoveToAsync (new [] { index }, destination, cancellationToken);
		}

		/// <summary>
		/// Move the specified messages to the destination folder.
		/// </summary>
		/// <remarks>
		/// Moves the specified messages to the destination folder.
		/// </remarks>
		/// <param name="indexes">The indexes of the messages to move.</param>
		/// <param name="destination">The destination folder.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="indexes"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="destination"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>The destination folder does not belong to the <see cref="IMailStore"/>.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void MoveTo (IList<int> indexes, IMailFolder destination, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously move the specified messages to the destination folder.
		/// </summary>
		/// <remarks>
		/// Asynchronously moves the specified messages to the destination folder.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="indexes">The indexes of the messages to move.</param>
		/// <param name="destination">The destination folder.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="indexes"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="destination"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>The destination folder does not belong to the <see cref="IMailStore"/>.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task MoveToAsync (IList<int> indexes, IMailFolder destination, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Fetch the message summaries for the specified message UIDs.
		/// </summary>
		/// <remarks>
		/// <para>Fetches the message summaries for the specified message UIDs.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <example>
		/// <code language="c#" source="Examples\ImapExamples.cs" region="DownloadBodyParts"/>
		/// </example>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="uids">The UIDs.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="items"/> is empty.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="uids"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<IMessageSummary> Fetch (IList<UniqueId> uids, MessageSummaryItems items, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously fetch the message summaries for the specified message UIDs.
		/// </summary>
		/// <remarks>
		/// <para>Asynchronously fetches the message summaries for the specified message
		/// UIDs.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="uids">The UIDs.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="items"/> is empty.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="uids"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<IMessageSummary>> FetchAsync (IList<UniqueId> uids, MessageSummaryItems items, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Fetch the message summaries for the specified message UIDs.
		/// </summary>
		/// <remarks>
		/// <para>Fetches the message summaries for the specified message UIDs.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="uids">The UIDs.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="headers">The desired header fields.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="headers"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="uids"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<IMessageSummary> Fetch (IList<UniqueId> uids, MessageSummaryItems items, IEnumerable<HeaderId> headers, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously fetch the message summaries for the specified message UIDs.
		/// </summary>
		/// <remarks>
		/// <para>Asynchronously fetches the message summaries for the specified message
		/// UIDs.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="uids">The UIDs.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="headers">The desired header fields.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="headers"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="uids"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<IMessageSummary>> FetchAsync (IList<UniqueId> uids, MessageSummaryItems items, IEnumerable<HeaderId> headers, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Fetch the message summaries for the specified message UIDs.
		/// </summary>
		/// <remarks>
		/// <para>Fetches the message summaries for the specified message UIDs.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="uids">The UIDs.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="headers">The desired header fields.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="headers"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>One or more of the specified <paramref name="headers"/> is invalid.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<IMessageSummary> Fetch (IList<UniqueId> uids, MessageSummaryItems items, IEnumerable<string> headers, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously fetch the message summaries for the specified message UIDs.
		/// </summary>
		/// <remarks>
		/// <para>Asynchronously fetches the message summaries for the specified message
		/// UIDs.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="uids">The UIDs.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="headers">The desired header fields.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="headers"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>One or more of the specified <paramref name="headers"/> is invalid.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<IMessageSummary>> FetchAsync (IList<UniqueId> uids, MessageSummaryItems items, IEnumerable<string> headers, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Fetch the message summaries for the specified message UIDs that have a
		/// higher mod-sequence value than the one specified.
		/// </summary>
		/// <remarks>
		/// <para>Fetches the message summaries for the specified message UIDs that
		/// have a higher mod-sequence value than the one specified.</para>
		/// <para>If the mail store supports quick resynchronization and the application has
		/// enabled this feature via <see cref="MailStore.EnableQuickResync(CancellationToken)"/>,
		/// then this method will emit <see cref="MessagesVanished"/> events for messages that
		/// have vanished since the specified mod-sequence value.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="uids">The UIDs.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="items"/> is empty.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="uids"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="IMailStore"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<IMessageSummary> Fetch (IList<UniqueId> uids, ulong modseq, MessageSummaryItems items, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously fetch the message summaries for the specified message UIDs that have a
		/// higher mod-sequence value than the one specified.
		/// </summary>
		/// <remarks>
		/// <para>Asynchronously fetches the message summaries for the specified message UIDs that
		/// have a higher mod-sequence value than the one specified.</para>
		/// <para>If the mail store supports quick resynchronization and the application has
		/// enabled this feature via <see cref="MailStore.EnableQuickResync(CancellationToken)"/>,
		/// then this method will emit <see cref="MessagesVanished"/> events for messages that
		/// have vanished since the specified mod-sequence value.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="uids">The UIDs.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="items"/> is empty.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="uids"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="IMailStore"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<IMessageSummary>> FetchAsync (IList<UniqueId> uids, ulong modseq, MessageSummaryItems items, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Fetch the message summaries for the specified message UIDs that have a
		/// higher mod-sequence value than the one specified.
		/// </summary>
		/// <remarks>
		/// <para>Fetches the message summaries for the specified message UIDs that
		/// have a higher mod-sequence value than the one specified.</para>
		/// <para>If the mail store supports quick resynchronization and the application has
		/// enabled this feature via <see cref="MailStore.EnableQuickResync(CancellationToken)"/>,
		/// then this method will emit <see cref="MessagesVanished"/> events for messages that
		/// have vanished since the specified mod-sequence value.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="uids">The UIDs.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="headers">The desired header fields.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="headers"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="uids"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="IMailStore"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<IMessageSummary> Fetch (IList<UniqueId> uids, ulong modseq, MessageSummaryItems items, IEnumerable<HeaderId> headers, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously fetch the message summaries for the specified message UIDs that have a
		/// higher mod-sequence value than the one specified.
		/// </summary>
		/// <remarks>
		/// <para>Asynchronously fetches the message summaries for the specified message UIDs that
		/// have a higher mod-sequence value than the one specified.</para>
		/// <para>If the mail store supports quick resynchronization and the application has
		/// enabled this feature via <see cref="MailStore.EnableQuickResync(CancellationToken)"/>,
		/// then this method will emit <see cref="MessagesVanished"/> events for messages that
		/// have vanished since the specified mod-sequence value.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="uids">The UIDs.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="headers">The desired header fields.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="headers"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="uids"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="IMailStore"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<IMessageSummary>> FetchAsync (IList<UniqueId> uids, ulong modseq, MessageSummaryItems items, IEnumerable<HeaderId> headers, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Fetch the message summaries for the specified message UIDs that have a
		/// higher mod-sequence value than the one specified.
		/// </summary>
		/// <remarks>
		/// <para>Fetches the message summaries for the specified message UIDs that
		/// have a higher mod-sequence value than the one specified.</para>
		/// <para>If the mail store supports quick resynchronization and the application has
		/// enabled this feature via <see cref="MailStore.EnableQuickResync(CancellationToken)"/>,
		/// then this method will emit <see cref="MessagesVanished"/> events for messages that
		/// have vanished since the specified mod-sequence value.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="uids">The UIDs.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="headers">The desired header fields.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="headers"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>One or more of the specified <paramref name="headers"/> is invalid.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="IMailStore"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<IMessageSummary> Fetch (IList<UniqueId> uids, ulong modseq, MessageSummaryItems items, IEnumerable<string> headers, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously fetch the message summaries for the specified message UIDs that have a
		/// higher mod-sequence value than the one specified.
		/// </summary>
		/// <remarks>
		/// <para>Asynchronously fetches the message summaries for the specified message UIDs that
		/// have a higher mod-sequence value than the one specified.</para>
		/// <para>If the mail store supports quick resynchronization and the application has
		/// enabled this feature via <see cref="MailStore.EnableQuickResync(CancellationToken)"/>,
		/// then this method will emit <see cref="MessagesVanished"/> events for messages that
		/// have vanished since the specified mod-sequence value.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="uids">The UIDs.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="headers">The desired header fields.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="headers"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>One or more of the specified <paramref name="headers"/> is invalid.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="IMailStore"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<IMessageSummary>> FetchAsync (IList<UniqueId> uids, ulong modseq, MessageSummaryItems items, IEnumerable<string> headers, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Fetch the message summaries for the specified message indexes.
		/// </summary>
		/// <remarks>
		/// <para>Fetches the message summaries for the specified message indexes.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="indexes">The indexes.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="indexes"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="items"/> is empty.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="indexes"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<IMessageSummary> Fetch (IList<int> indexes, MessageSummaryItems items, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously fetch the message summaries for the specified message indexes.
		/// </summary>
		/// <remarks>
		/// <para>Asynchronously fetches the message summaries for the specified message
		/// indexes.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="indexes">The indexes.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="indexes"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="items"/> is empty.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="indexes"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<IMessageSummary>> FetchAsync (IList<int> indexes, MessageSummaryItems items, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Fetch the message summaries for the specified message indexes.
		/// </summary>
		/// <remarks>
		/// <para>Fetches the message summaries for the specified message indexes.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="indexes">The indexes.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="headers">The desired header fields.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="indexes"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="headers"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="indexes"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<IMessageSummary> Fetch (IList<int> indexes, MessageSummaryItems items, IEnumerable<HeaderId> headers, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously fetch the message summaries for the specified message indexes.
		/// </summary>
		/// <remarks>
		/// <para>Asynchronously fetches the message summaries for the specified message
		/// indexes.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="indexes">The indexes.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="headers">The desired header fields.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="indexes"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="headers"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="indexes"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<IMessageSummary>> FetchAsync (IList<int> indexes, MessageSummaryItems items, IEnumerable<HeaderId> headers, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Fetch the message summaries for the specified message indexes.
		/// </summary>
		/// <remarks>
		/// <para>Fetches the message summaries for the specified message indexes.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="indexes">The indexes.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="headers">The desired header fields.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="indexes"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="headers"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>One or more of the specified <paramref name="headers"/> is invalid.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<IMessageSummary> Fetch (IList<int> indexes, MessageSummaryItems items, IEnumerable<string> headers, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously fetch the message summaries for the specified message indexes.
		/// </summary>
		/// <remarks>
		/// <para>Asynchronously fetches the message summaries for the specified message
		/// indexes.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="indexes">The indexes.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="headers">The desired header fields.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="indexes"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="headers"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>One or more of the specified <paramref name="headers"/> is invalid.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<IMessageSummary>> FetchAsync (IList<int> indexes, MessageSummaryItems items, IEnumerable<string> headers, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Fetch the message summaries for the specified message indexes that have a
		/// higher mod-sequence value than the one specified.
		/// </summary>
		/// <remarks>
		/// <para>Fetches the message summaries for the specified message indexes that
		/// have a higher mod-sequence value than the one specified.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="indexes">The indexes.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="indexes"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="items"/> is empty.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="indexes"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<IMessageSummary> Fetch (IList<int> indexes, ulong modseq, MessageSummaryItems items, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously fetch the message summaries for the specified message indexes that
		/// have a higher mod-sequence value than the one specified.
		/// </summary>
		/// <remarks>
		/// <para>Asynchronously fetches the message summaries for the specified message
		/// indexes that have a higher mod-sequence value than the one specified.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="indexes">The indexes.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="indexes"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="items"/> is empty.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="indexes"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<IMessageSummary>> FetchAsync (IList<int> indexes, ulong modseq, MessageSummaryItems items, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Fetch the message summaries for the specified message indexes that
		/// have a higher mod-sequence value than the one specified.
		/// </summary>
		/// <remarks>
		/// <para>Fetches the message summaries for the specified message indexes that
		/// have a higher mod-sequence value than the one specified.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="indexes">The indexes.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="headers">The desired header fields.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="indexes"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="headers"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="indexes"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<IMessageSummary> Fetch (IList<int> indexes, ulong modseq, MessageSummaryItems items, IEnumerable<HeaderId> headers, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously fetch the message summaries for the specified message indexes that
		/// have a higher mod-sequence value than the one specified.
		/// </summary>
		/// <remarks>
		/// <para>Asynchronously fetches the message summaries for the specified message
		/// indexes that have a higher mod-sequence value than the one specified.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="indexes">The indexes.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="headers">The desired header fields.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="indexes"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="headers"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="indexes"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<IMessageSummary>> FetchAsync (IList<int> indexes, ulong modseq, MessageSummaryItems items, IEnumerable<HeaderId> headers, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Fetch the message summaries for the specified message indexes that
		/// have a higher mod-sequence value than the one specified.
		/// </summary>
		/// <remarks>
		/// <para>Fetches the message summaries for the specified message indexes that
		/// have a higher mod-sequence value than the one specified.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="indexes">The indexes.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="headers">The desired header fields.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="indexes"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="headers"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>One or more of the specified <paramref name="headers"/> is invalid.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<IMessageSummary> Fetch (IList<int> indexes, ulong modseq, MessageSummaryItems items, IEnumerable<string> headers, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously fetch the message summaries for the specified message indexes that
		/// have a higher mod-sequence value than the one specified.
		/// </summary>
		/// <remarks>
		/// <para>Asynchronously fetches the message summaries for the specified message
		/// indexes that have a higher mod-sequence value than the one specified.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="indexes">The indexes.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="headers">The desired header fields.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="indexes"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="headers"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>One or more of the specified <paramref name="headers"/> is invalid.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<IMessageSummary>> FetchAsync (IList<int> indexes, ulong modseq, MessageSummaryItems items, IEnumerable<string> headers, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Fetch the message summaries for the messages between the two indexes, inclusive.
		/// </summary>
		/// <remarks>
		/// <para>Fetches the message summaries for the messages between the two
		/// indexes, inclusive.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="min">The minimum index.</param>
		/// <param name="max">The maximum index, or <c>-1</c> to specify no upper bound.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <para><paramref name="min"/> is out of range.</para>
		/// <para>-or-</para>
		/// <para><paramref name="max"/> is out of range.</para>
		/// <para>-or-</para>
		/// <para><paramref name="items"/> is empty.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<IMessageSummary> Fetch (int min, int max, MessageSummaryItems items, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously fetch the message summaries for the messages between the two indexes, inclusive.
		/// </summary>
		/// <remarks>
		/// <para>Asynchronously fetches the message summaries for the messages between
		/// the two indexes, inclusive.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="min">The minimum index.</param>
		/// <param name="max">The maximum index, or <c>-1</c> to specify no upper bound.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <para><paramref name="min"/> is out of range.</para>
		/// <para>-or-</para>
		/// <para><paramref name="max"/> is out of range.</para>
		/// <para>-or-</para>
		/// <para><paramref name="items"/> is empty.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<IMessageSummary>> FetchAsync (int min, int max, MessageSummaryItems items, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Fetch the message summaries for the messages between the two indexes, inclusive.
		/// </summary>
		/// <remarks>
		/// <para>Fetches the message summaries for the messages between the two
		/// indexes, inclusive.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="min">The minimum index.</param>
		/// <param name="max">The maximum index, or <c>-1</c> to specify no upper bound.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="headers">The desired header fields.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <para><paramref name="min"/> is out of range.</para>
		/// <para>-or-</para>
		/// <para><paramref name="max"/> is out of range.</para>
		/// </exception>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="headers"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<IMessageSummary> Fetch (int min, int max, MessageSummaryItems items, IEnumerable<HeaderId> headers, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously fetch the message summaries for the messages between the two indexes, inclusive.
		/// </summary>
		/// <remarks>
		/// <para>Asynchronously fetches the message summaries for the messages between
		/// the two indexes, inclusive.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="min">The minimum index.</param>
		/// <param name="max">The maximum index, or <c>-1</c> to specify no upper bound.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="headers">The desired header fields.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <para><paramref name="min"/> is out of range.</para>
		/// <para>-or-</para>
		/// <para><paramref name="max"/> is out of range.</para>
		/// </exception>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="headers"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<IMessageSummary>> FetchAsync (int min, int max, MessageSummaryItems items, IEnumerable<HeaderId> headers, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Fetch the message summaries for the messages between the two indexes, inclusive.
		/// </summary>
		/// <remarks>
		/// <para>Fetches the message summaries for the messages between the two
		/// indexes, inclusive.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="min">The minimum index.</param>
		/// <param name="max">The maximum index, or <c>-1</c> to specify no upper bound.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="headers">The desired header fields.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <para><paramref name="min"/> is out of range.</para>
		/// <para>-or-</para>
		/// <para><paramref name="max"/> is out of range.</para>
		/// </exception>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="headers"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the specified <paramref name="headers"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<IMessageSummary> Fetch (int min, int max, MessageSummaryItems items, IEnumerable<string> headers, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously fetch the message summaries for the messages between the two indexes, inclusive.
		/// </summary>
		/// <remarks>
		/// <para>Asynchronously fetches the message summaries for the messages between
		/// the two indexes, inclusive.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="min">The minimum index.</param>
		/// <param name="max">The maximum index, or <c>-1</c> to specify no upper bound.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="headers">The desired header fields.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <para><paramref name="min"/> is out of range.</para>
		/// <para>-or-</para>
		/// <para><paramref name="max"/> is out of range.</para>
		/// </exception>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="headers"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the specified <paramref name="headers"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<IMessageSummary>> FetchAsync (int min, int max, MessageSummaryItems items, IEnumerable<string> headers, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Fetch the message summaries for the messages between the two indexes (inclusive)
		/// that have a higher mod-sequence value than the one specified.
		/// </summary>
		/// <remarks>
		/// <para>Fetches the message summaries for the messages between the two
		/// indexes (inclusive) that have a higher mod-sequence value than the one
		/// specified.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="min">The minimum index.</param>
		/// <param name="max">The maximum index, or <c>-1</c> to specify no upper bound.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <para><paramref name="min"/> is out of range.</para>
		/// <para>-or-</para>
		/// <para><paramref name="max"/> is out of range.</para>
		/// <para>-or-</para>
		/// <para><paramref name="items"/> is empty.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<IMessageSummary> Fetch (int min, int max, ulong modseq, MessageSummaryItems items, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously fetch the message summaries for the messages between the two indexes
		/// (inclusive) that have a higher mod-sequence value than the one specified.
		/// </summary>
		/// <remarks>
		/// <para>Asynchronously fetches the message summaries for the messages between
		/// the two indexes (inclusive) that have a higher mod-sequence value than the
		/// one specified.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="min">The minimum index.</param>
		/// <param name="max">The maximum index, or <c>-1</c> to specify no upper bound.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <para><paramref name="min"/> is out of range.</para>
		/// <para>-or-</para>
		/// <para><paramref name="max"/> is out of range.</para>
		/// <para>-or-</para>
		/// <para><paramref name="items"/> is empty.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<IMessageSummary>> FetchAsync (int min, int max, ulong modseq, MessageSummaryItems items, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Fetch the message summaries for the messages between the two indexes (inclusive)
		/// that have a higher mod-sequence value than the one specified.
		/// </summary>
		/// <remarks>
		/// <para>Fetches the message summaries for the messages between the two
		/// indexes (inclusive) that have a higher mod-sequence value than the one
		/// specified.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="min">The minimum index.</param>
		/// <param name="max">The maximum index, or <c>-1</c> to specify no upper bound.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="headers">The desired header fields.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <para><paramref name="min"/> is out of range.</para>
		/// <para>-or-</para>
		/// <para><paramref name="max"/> is out of range.</para>
		/// </exception>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="headers"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<IMessageSummary> Fetch (int min, int max, ulong modseq, MessageSummaryItems items, IEnumerable<HeaderId> headers, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously fetch the message summaries for the messages between the two indexes
		/// (inclusive) that have a higher mod-sequence value than the one specified.
		/// </summary>
		/// <remarks>
		/// <para>Asynchronously fetches the message summaries for the messages between
		/// the two indexes (inclusive) that have a higher mod-sequence value than the
		/// one specified.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="min">The minimum index.</param>
		/// <param name="max">The maximum index, or <c>-1</c> to specify no upper bound.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="headers">The desired header fields.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <para><paramref name="min"/> is out of range.</para>
		/// <para>-or-</para>
		/// <para><paramref name="max"/> is out of range.</para>
		/// </exception>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="headers"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<IMessageSummary>> FetchAsync (int min, int max, ulong modseq, MessageSummaryItems items, IEnumerable<HeaderId> headers, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Fetch the message summaries for the messages between the two indexes (inclusive)
		/// that have a higher mod-sequence value than the one specified.
		/// </summary>
		/// <remarks>
		/// <para>Fetches the message summaries for the messages between the two
		/// indexes (inclusive) that have a higher mod-sequence value than the one
		/// specified.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="min">The minimum index.</param>
		/// <param name="max">The maximum index, or <c>-1</c> to specify no upper bound.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="headers">The desired header fields.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <para><paramref name="min"/> is out of range.</para>
		/// <para>-or-</para>
		/// <para><paramref name="max"/> is out of range.</para>
		/// </exception>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="headers"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the specified <paramref name="headers"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<IMessageSummary> Fetch (int min, int max, ulong modseq, MessageSummaryItems items, IEnumerable<string> headers, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously fetch the message summaries for the messages between the two indexes
		/// (inclusive) that have a higher mod-sequence value than the one specified.
		/// </summary>
		/// <remarks>
		/// <para>Asynchronously fetches the message summaries for the messages between
		/// the two indexes (inclusive) that have a higher mod-sequence value than the
		/// one specified.</para>
		/// <para>It should be noted that if another client has modified any message
		/// in the folder, the mail service may choose to return information that was
		/// not explicitly requested. It is therefore important to be prepared to
		/// handle both additional fields on a <see cref="IMessageSummary"/> for
		/// messages that were requested as well as summaries for messages that were
		/// not requested at all.</para>
		/// </remarks>
		/// <returns>An enumeration of summaries for the requested messages.</returns>
		/// <param name="min">The minimum index.</param>
		/// <param name="max">The maximum index, or <c>-1</c> to specify no upper bound.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="items">The message summary items to fetch.</param>
		/// <param name="headers">The desired header fields.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <para><paramref name="min"/> is out of range.</para>
		/// <para>-or-</para>
		/// <para><paramref name="max"/> is out of range.</para>
		/// </exception>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="headers"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the specified <paramref name="headers"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<IMessageSummary>> FetchAsync (int min, int max, ulong modseq, MessageSummaryItems items, IEnumerable<string> headers, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Get the specified message headers.
		/// </summary>
		/// <remarks>
		/// Gets the specified message headers.
		/// </remarks>
		/// <returns>The message headers.</returns>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested message headers.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract HeaderList GetHeaders (UniqueId uid, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Asynchronously get the specified message headers.
		/// </summary>
		/// <remarks>
		/// Asynchronously gets the specified message headers.
		/// </remarks>
		/// <returns>The message headers.</returns>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested message headers.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<HeaderList> GetHeadersAsync (UniqueId uid, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Get the specified body part headers.
		/// </summary>
		/// <remarks>
		/// Gets the specified body part headers.
		/// </remarks>
		/// <returns>The body part headers.</returns>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="part">The body part.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="part"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested body part headers.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract HeaderList GetHeaders (UniqueId uid, BodyPart part, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Asynchronously get the specified body part headers.
		/// </summary>
		/// <remarks>
		/// Asynchronously gets the specified body part headers.
		/// </remarks>
		/// <returns>The body part headers.</returns>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="part">The body part.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="part"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested body part headers.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<HeaderList> GetHeadersAsync (UniqueId uid, BodyPart part, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Get the specified message headers.
		/// </summary>
		/// <remarks>
		/// Gets the specified message headers.
		/// </remarks>
		/// <returns>The message headers.</returns>
		/// <param name="index">The index of the message.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="index"/> is out of range.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested message headers.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract HeaderList GetHeaders (int index, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Asynchronously get the specified message headers.
		/// </summary>
		/// <remarks>
		/// Asynchronously gets the specified message headers.
		/// </remarks>
		/// <returns>The message headers.</returns>
		/// <param name="index">The index of the message.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="index"/> is out of range.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested message headers.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<HeaderList> GetHeadersAsync (int index, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Get the specified body part headers.
		/// </summary>
		/// <remarks>
		/// Gets the specified body part headers.
		/// </remarks>
		/// <returns>The body part headers.</returns>
		/// <param name="index">The index of the message.</param>
		/// <param name="part">The body part.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="index"/> is out of range.
		/// </exception>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="part"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested body part headers.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract HeaderList GetHeaders (int index, BodyPart part, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Asynchronously get the specified body part headers.
		/// </summary>
		/// <remarks>
		/// Asynchronously gets the specified body part headers.
		/// </remarks>
		/// <returns>The body part headers.</returns>
		/// <param name="index">The index of the message.</param>
		/// <param name="part">The body part.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="index"/> is out of range.
		/// </exception>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="part"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested body part headers.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<HeaderList> GetHeadersAsync (int index, BodyPart part, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Get the specified message.
		/// </summary>
		/// <remarks>
		/// Gets the specified message.
		/// </remarks>
		/// <returns>The message.</returns>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested message.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract MimeMessage GetMessage (UniqueId uid, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Asynchronously get the specified message.
		/// </summary>
		/// <remarks>
		/// Asynchronously gets the specified message.
		/// </remarks>
		/// <returns>The message.</returns>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested message.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<MimeMessage> GetMessageAsync (UniqueId uid, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Get the specified message.
		/// </summary>
		/// <remarks>
		/// Gets the specified message.
		/// </remarks>
		/// <returns>The message.</returns>
		/// <param name="index">The index of the message.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="index"/> is out of range.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested message.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract MimeMessage GetMessage (int index, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Asynchronously get the specified message.
		/// </summary>
		/// <remarks>
		/// Asynchronously gets the specified message.
		/// </remarks>
		/// <returns>The message.</returns>
		/// <param name="index">The index of the message.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="index"/> is out of range.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested message.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<MimeMessage> GetMessageAsync (int index, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Get the specified body part.
		/// </summary>
		/// <remarks>
		/// Gets the specified body part.
		/// </remarks>
		/// <example>
		/// <code language="c#" source="Examples\ImapExamples.cs" region="DownloadBodyParts"/>
		/// </example>
		/// <returns>The body part.</returns>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="part">The body part.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="part"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested message body.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract MimeEntity GetBodyPart (UniqueId uid, BodyPart part, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Asynchronously get the specified body part.
		/// </summary>
		/// <remarks>
		/// Asynchronously gets the specified body part.
		/// </remarks>
		/// <returns>The body part.</returns>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="part">The body part.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="part"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested message body.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<MimeEntity> GetBodyPartAsync (UniqueId uid, BodyPart part, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Get the specified body part.
		/// </summary>
		/// <remarks>
		/// Gets the specified body part.
		/// </remarks>
		/// <returns>The body part.</returns>
		/// <param name="index">The index of the message.</param>
		/// <param name="part">The body part.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="part"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="index"/> is out of range.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested message body.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract MimeEntity GetBodyPart (int index, BodyPart part, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Asynchronously get the specified body part.
		/// </summary>
		/// <remarks>
		/// Asynchronously gets the specified body part.
		/// </remarks>
		/// <returns>The body part.</returns>
		/// <param name="index">The index of the message.</param>
		/// <param name="part">The body part.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="part"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="index"/> is out of range.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested message body.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<MimeEntity> GetBodyPartAsync (int index, BodyPart part, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Get a substream of the specified message.
		/// </summary>
		/// <remarks>
		/// Gets a substream of the message. If the starting offset is beyond
		/// the end of the message, an empty stream is returned. If the number of
		/// bytes desired extends beyond the end of the message, a truncated stream
		/// will be returned.
		/// </remarks>
		/// <returns>The stream.</returns>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="offset">The starting offset of the first desired byte.</param>
		/// <param name="count">The number of bytes desired.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <para><paramref name="offset"/> is negative.</para>
		/// <para>-or-</para>
		/// <para><paramref name="count"/> is negative.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested message stream.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Stream GetStream (UniqueId uid, int offset, int count, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Asynchronously get a substream of the specified message.
		/// </summary>
		/// <remarks>
		/// Asynchronously gets a substream of the message. If the starting offset is beyond
		/// the end of the message, an empty stream is returned. If the number of
		/// bytes desired extends beyond the end of the message, a truncated stream
		/// will be returned.
		/// </remarks>
		/// <returns>The stream.</returns>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="offset">The starting offset of the first desired byte.</param>
		/// <param name="count">The number of bytes desired.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <para><paramref name="offset"/> is negative.</para>
		/// <para>-or-</para>
		/// <para><paramref name="count"/> is negative.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested message stream.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<Stream> GetStreamAsync (UniqueId uid, int offset, int count, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Get a substream of the specified message.
		/// </summary>
		/// <remarks>
		/// Gets a substream of the message. If the starting offset is beyond
		/// the end of the message, an empty stream is returned. If the number of
		/// bytes desired extends beyond the end of the message, a truncated stream
		/// will be returned.
		/// </remarks>
		/// <returns>The stream.</returns>
		/// <param name="index">The index of the message.</param>
		/// <param name="offset">The starting offset of the first desired byte.</param>
		/// <param name="count">The number of bytes desired.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <para><paramref name="index"/> is out of range.</para>
		/// <para>-or-</para>
		/// <para><paramref name="offset"/> is negative.</para>
		/// <para>-or-</para>
		/// <para><paramref name="count"/> is negative.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested message stream.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Stream GetStream (int index, int offset, int count, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Asynchronously get a substream of the specified message.
		/// </summary>
		/// <remarks>
		/// Asynchronously gets a substream of the message. If the starting offset is beyond
		/// the end of the message, an empty stream is returned. If the number of
		/// bytes desired extends beyond the end of the message, a truncated stream
		/// will be returned.
		/// </remarks>
		/// <returns>The stream.</returns>
		/// <param name="index">The index of the message.</param>
		/// <param name="offset">The starting offset of the first desired byte.</param>
		/// <param name="count">The number of bytes desired.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <para><paramref name="index"/> is out of range.</para>
		/// <para>-or-</para>
		/// <para><paramref name="offset"/> is negative.</para>
		/// <para>-or-</para>
		/// <para><paramref name="count"/> is negative.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested message stream.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<Stream> GetStreamAsync (int index, int offset, int count, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Get a substream of the specified body part.
		/// </summary>
		/// <remarks>
		/// Gets a substream of the body part. If the starting offset is beyond
		/// the end of the body part, an empty stream is returned. If the number of
		/// bytes desired extends beyond the end of the body part, a truncated stream
		/// will be returned.
		/// </remarks>
		/// <returns>The stream.</returns>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="part">The desired body part.</param>
		/// <param name="offset">The starting offset of the first desired byte.</param>
		/// <param name="count">The number of bytes desired.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="part"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <para><paramref name="offset"/> is negative.</para>
		/// <para>-or-</para>
		/// <para><paramref name="count"/> is negative.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested message stream.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Stream GetStream (UniqueId uid, BodyPart part, int offset, int count, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null)
		{
			if (uid.Id == 0)
				throw new ArgumentException ("The uid is invalid.", nameof (uid));

			if (part == null)
				throw new ArgumentNullException (nameof (part));

			if (offset < 0)
				throw new ArgumentOutOfRangeException (nameof (offset));

			if (count < 0)
				throw new ArgumentOutOfRangeException (nameof (count));

			return GetStream (uid, part.PartSpecifier, offset, count, cancellationToken, progress);
		}

		/// <summary>
		/// Asynchronously get a substream of the specified body part.
		/// </summary>
		/// <remarks>
		/// Asynchronously gets a substream of the body part. If the starting offset is beyond
		/// the end of the body part, an empty stream is returned. If the number of
		/// bytes desired extends beyond the end of the body part, a truncated stream
		/// will be returned.
		/// </remarks>
		/// <returns>The stream.</returns>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="part">The desired body part.</param>
		/// <param name="offset">The starting offset of the first desired byte.</param>
		/// <param name="count">The number of bytes desired.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="part"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <para><paramref name="offset"/> is negative.</para>
		/// <para>-or-</para>
		/// <para><paramref name="count"/> is negative.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested message stream.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task<Stream> GetStreamAsync (UniqueId uid, BodyPart part, int offset, int count, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null)
		{
			if (part == null)
				throw new ArgumentNullException (nameof (part));

			if (offset < 0)
				throw new ArgumentOutOfRangeException (nameof (offset));

			if (count < 0)
				throw new ArgumentOutOfRangeException (nameof (count));

			return GetStreamAsync (uid, part.PartSpecifier, offset, count, cancellationToken, progress);
		}

		/// <summary>
		/// Get a substream of the specified body part.
		/// </summary>
		/// <remarks>
		/// Gets a substream of the body part. If the starting offset is beyond
		/// the end of the body part, an empty stream is returned. If the number of
		/// bytes desired extends beyond the end of the body part, a truncated stream
		/// will be returned.
		/// </remarks>
		/// <returns>The stream.</returns>
		/// <param name="index">The index of the message.</param>
		/// <param name="part">The desired body part.</param>
		/// <param name="offset">The starting offset of the first desired byte.</param>
		/// <param name="count">The number of bytes desired.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="part"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <para><paramref name="index"/> is out of range.</para>
		/// <para>-or-</para>
		/// <para><paramref name="offset"/> is negative.</para>
		/// <para>-or-</para>
		/// <para><paramref name="count"/> is negative.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested message stream.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Stream GetStream (int index, BodyPart part, int offset, int count, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null)
		{
			if (index < 0 || index >= Count)
				throw new ArgumentOutOfRangeException (nameof (index));

			if (part == null)
				throw new ArgumentNullException (nameof (part));

			if (offset < 0)
				throw new ArgumentOutOfRangeException (nameof (offset));

			if (count < 0)
				throw new ArgumentOutOfRangeException (nameof (count));

			return GetStream (index, part.PartSpecifier, offset, count, cancellationToken, progress);
		}

		/// <summary>
		/// Asynchronously get a substream of the specified body part.
		/// </summary>
		/// <remarks>
		/// Asynchronously gets a substream of the body part. If the starting offset is beyond
		/// the end of the body part, an empty stream is returned. If the number of
		/// bytes desired extends beyond the end of the body part, a truncated stream
		/// will be returned.
		/// </remarks>
		/// <returns>The stream.</returns>
		/// <param name="index">The index of the message.</param>
		/// <param name="part">The desired body part.</param>
		/// <param name="offset">The starting offset of the first desired byte.</param>
		/// <param name="count">The number of bytes desired.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="part"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <para><paramref name="index"/> is out of range.</para>
		/// <para>-or-</para>
		/// <para><paramref name="offset"/> is negative.</para>
		/// <para>-or-</para>
		/// <para><paramref name="count"/> is negative.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested message stream.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task<Stream> GetStreamAsync (int index, BodyPart part, int offset, int count, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null)
		{
			if (index < 0 || index >= Count)
				throw new ArgumentOutOfRangeException (nameof (index));

			if (part == null)
				throw new ArgumentNullException (nameof (part));

			if (offset < 0)
				throw new ArgumentOutOfRangeException (nameof (offset));

			if (count < 0)
				throw new ArgumentOutOfRangeException (nameof (count));

			return GetStreamAsync (index, part.PartSpecifier, offset, count, cancellationToken, progress);
		}

		/// <summary>
		/// Get a substream of the specified message.
		/// </summary>
		/// <remarks>
		/// <para>Gets a substream of the specified message.</para>
		/// <para>For more information about how to construct the <paramref name="section"/>,
		/// see Section 6.4.5 of RFC3501.</para>
		/// </remarks>
		/// <returns>The stream.</returns>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="section">The desired section of the message.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="section"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested message stream.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Stream GetStream (UniqueId uid, string section, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Asynchronously get a substream of the specified message.
		/// </summary>
		/// <remarks>
		/// <para>Asynchronously gets a substream of the specified message.</para>
		/// <para>For more information about how to construct the <paramref name="section"/>,
		/// see Section 6.4.5 of RFC3501.</para>
		/// </remarks>
		/// <returns>The stream.</returns>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="section">The desired section of the message.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="section"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested message stream.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<Stream> GetStreamAsync (UniqueId uid, string section, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Get a substream of the specified message.
		/// </summary>
		/// <remarks>
		/// <para>Gets a substream of the specified message. If the starting offset is beyond
		/// the end of the specified section of the message, an empty stream is returned. If
		/// the number of bytes desired extends beyond the end of the section, a truncated
		/// stream will be returned.</para>
		/// <para>For more information about how to construct the <paramref name="section"/>,
		/// see Section 6.4.5 of RFC3501.</para>
		/// </remarks>
		/// <returns>The stream.</returns>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="section">The desired section of the message.</param>
		/// <param name="offset">The starting offset of the first desired byte.</param>
		/// <param name="count">The number of bytes desired.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="section"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <para><paramref name="offset"/> is negative.</para>
		/// <para>-or-</para>
		/// <para><paramref name="count"/> is negative.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested message stream.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Stream GetStream (UniqueId uid, string section, int offset, int count, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Asynchronously get a substream of the specified message.
		/// </summary>
		/// <remarks>
		/// <para>Asynchronously gets a substream of the specified message. If the starting
		/// offset is beyond the end of the specified section of the message, an empty stream
		/// is returned. If the number of bytes desired extends beyond the end of the section,
		/// a truncated stream will be returned.</para>
		/// <para>For more information about how to construct the <paramref name="section"/>,
		/// see Section 6.4.5 of RFC3501.</para>
		/// </remarks>
		/// <returns>The stream.</returns>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="section">The desired section of the message.</param>
		/// <param name="offset">The starting offset of the first desired byte.</param>
		/// <param name="count">The number of bytes desired.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="section"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <para><paramref name="offset"/> is negative.</para>
		/// <para>-or-</para>
		/// <para><paramref name="count"/> is negative.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested message stream.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<Stream> GetStreamAsync (UniqueId uid, string section, int offset, int count, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Get a substream of the specified message.
		/// </summary>
		/// <remarks>
		/// <para>Gets a substream of the specified message.</para>
		/// <para>For more information about how to construct the <paramref name="section"/>,
		/// see Section 6.4.5 of RFC3501.</para>
		/// </remarks>
		/// <returns>The stream.</returns>
		/// <param name="index">The index of the message.</param>
		/// <param name="section">The desired section of the message.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="section"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="index"/> is out of range.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested message stream.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Stream GetStream (int index, string section, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Asynchronously get a substream of the specified body part.
		/// </summary>
		/// <remarks>
		/// <para>Asynchronously gets a substream of the specified message.</para>
		/// <para>For more information about how to construct the <paramref name="section"/>,
		/// see Section 6.4.5 of RFC3501.</para>
		/// </remarks>
		/// <returns>The stream.</returns>
		/// <param name="index">The index of the message.</param>
		/// <param name="section">The desired section of the message.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="section"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="index"/> is out of range.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested message stream.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<Stream> GetStreamAsync (int index, string section, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Get a substream of the specified message.
		/// </summary>
		/// <remarks>
		/// <para>Gets a substream of the specified message. If the starting offset is beyond
		/// the end of the specified section of the message, an empty stream is returned. If
		/// the number of bytes desired extends beyond the end of the section, a truncated
		/// stream will be returned.</para>
		/// <para>For more information about how to construct the <paramref name="section"/>,
		/// see Section 6.4.5 of RFC3501.</para>
		/// </remarks>
		/// <returns>The stream.</returns>
		/// <param name="index">The index of the message.</param>
		/// <param name="section">The desired section of the message.</param>
		/// <param name="offset">The starting offset of the first desired byte.</param>
		/// <param name="count">The number of bytes desired.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="section"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <para><paramref name="index"/> is out of range.</para>
		/// <para>-or-</para>
		/// <para><paramref name="offset"/> is negative.</para>
		/// <para>-or-</para>
		/// <para><paramref name="count"/> is negative.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested message stream.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Stream GetStream (int index, string section, int offset, int count, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Asynchronously get a substream of the specified body part.
		/// </summary>
		/// <remarks>
		/// <para>Asynchronously gets a substream of the specified message. If the starting
		/// offset is beyond the end of the specified section of the message, an empty stream
		/// is returned. If the number of bytes desired extends beyond the end of the section,
		/// a truncated stream will be returned.</para>
		/// <para>For more information about how to construct the <paramref name="section"/>,
		/// see Section 6.4.5 of RFC3501.</para>
		/// </remarks>
		/// <returns>The stream.</returns>
		/// <param name="index">The index of the message.</param>
		/// <param name="section">The desired section of the message.</param>
		/// <param name="offset">The starting offset of the first desired byte.</param>
		/// <param name="count">The number of bytes desired.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <param name="progress">The progress reporting mechanism.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="section"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <para><paramref name="index"/> is out of range.</para>
		/// <para>-or-</para>
		/// <para><paramref name="offset"/> is negative.</para>
		/// <para>-or-</para>
		/// <para><paramref name="count"/> is negative.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="MessageNotFoundException">
		/// The <see cref="IMailStore"/> did not return the requested message stream.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<Stream> GetStreamAsync (int index, string section, int offset, int count, CancellationToken cancellationToken = default (CancellationToken), ITransferProgress progress = null);

		/// <summary>
		/// Add a set of flags to the specified message.
		/// </summary>
		/// <remarks>
		/// Adds a set of flags to the specified message.
		/// </remarks>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="flags">The message flags to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="uid"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual void AddFlags (UniqueId uid, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			AddFlags (new [] { uid }, flags, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously add a set of flags to the specified message.
		/// </summary>
		/// <remarks>
		/// Asynchronously adds a set of flags to the specified message.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="flags">The message flags to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="uid"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task AddFlagsAsync (UniqueId uid, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return AddFlagsAsync (new [] { uid }, flags, silent, cancellationToken);
		}

		/// <summary>
		/// Add a set of flags to the specified message.
		/// </summary>
		/// <remarks>
		/// Adds a set of flags to the specified message.
		/// </remarks>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="flags">The message flags to add.</param>
		/// <param name="keywords">A set of user-defined flags to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="uid"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual void AddFlags (UniqueId uid, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			AddFlags (new [] { uid }, flags, keywords, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously add a set of flags to the specified message.
		/// </summary>
		/// <remarks>
		/// Asynchronously adds a set of flags to the specified message.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="flags">The message flags to add.</param>
		/// <param name="keywords">A set of user-defined flags to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="uid"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task AddFlagsAsync (UniqueId uid, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return AddFlagsAsync (new [] { uid }, flags, keywords, silent, cancellationToken);
		}

		/// <summary>
		/// Add a set of flags to the specified messages.
		/// </summary>
		/// <remarks>
		/// Adds a set of flags to the specified messages.
		/// </remarks>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="flags">The message flags to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual void AddFlags (IList<UniqueId> uids, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			AddFlags (uids, flags, null, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously add a set of flags to the specified messages.
		/// </summary>
		/// <remarks>
		/// Asynchronously adds a set of flags to the specified messages.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="flags">The message flags to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task AddFlagsAsync (IList<UniqueId> uids, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return AddFlagsAsync (uids, flags, null, silent, cancellationToken);
		}

		/// <summary>
		/// Add a set of flags to the specified messages.
		/// </summary>
		/// <remarks>
		/// Adds a set of flags to the specified messages.
		/// </remarks>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="flags">The message flags to add.</param>
		/// <param name="keywords">A set of user-defined flags to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void AddFlags (IList<UniqueId> uids, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously add a set of flags to the specified messages.
		/// </summary>
		/// <remarks>
		/// Asynchronously adds a set of flags to the specified messages.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="flags">The message flags to add.</param>
		/// <param name="keywords">A set of user-defined flags to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task AddFlagsAsync (IList<UniqueId> uids, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Remove a set of flags from the specified message.
		/// </summary>
		/// <remarks>
		/// Removes a set of flags from the specified message.
		/// </remarks>
		/// <param name="uid">The UIDs of the message.</param>
		/// <param name="flags">The message flags to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="uid"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual void RemoveFlags (UniqueId uid, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			RemoveFlags (new [] { uid }, flags, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously remove a set of flags from the specified message.
		/// </summary>
		/// <remarks>
		/// Asynchronously removes a set of flags from the specified message.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="flags">The message flags to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="uid"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task RemoveFlagsAsync (UniqueId uid, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return RemoveFlagsAsync (new [] { uid }, flags, silent, cancellationToken);
		}

		/// <summary>
		/// Remove a set of flags from the specified message.
		/// </summary>
		/// <remarks>
		/// Removes a set of flags from the specified message.
		/// </remarks>
		/// <param name="uid">The UIDs of the message.</param>
		/// <param name="flags">The message flags to remove.</param>
		/// <param name="keywords">A set of user-defined flags to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="uid"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual void RemoveFlags (UniqueId uid, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			RemoveFlags (new [] { uid }, flags, keywords, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously remove a set of flags from the specified message.
		/// </summary>
		/// <remarks>
		/// Asynchronously removes a set of flags from the specified message.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="flags">The message flags to remove.</param>
		/// <param name="keywords">A set of user-defined flags to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="uid"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task RemoveFlagsAsync (UniqueId uid, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return RemoveFlagsAsync (new [] { uid }, flags, keywords, silent, cancellationToken);
		}

		/// <summary>
		/// Remove a set of flags from the specified messages.
		/// </summary>
		/// <remarks>
		/// Removes a set of flags from the specified messages.
		/// </remarks>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="flags">The message flags to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual void RemoveFlags (IList<UniqueId> uids, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			RemoveFlags (uids, flags, null, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously remove a set of flags from the specified messages.
		/// </summary>
		/// <remarks>
		/// Asynchronously removes a set of flags from the specified messages.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="flags">The message flags to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task RemoveFlagsAsync (IList<UniqueId> uids, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return RemoveFlagsAsync (uids, flags, null, silent, cancellationToken);
		}

		/// <summary>
		/// Remove a set of flags from the specified messages.
		/// </summary>
		/// <remarks>
		/// Removes a set of flags from the specified messages.
		/// </remarks>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="flags">The message flags to remove.</param>
		/// <param name="keywords">A set of user-defined flags to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void RemoveFlags (IList<UniqueId> uids, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously remove a set of flags from the specified messages.
		/// </summary>
		/// <remarks>
		/// Asynchronously removes a set of flags from the specified messages.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="flags">The message flags to remove.</param>
		/// <param name="keywords">A set of user-defined flags to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task RemoveFlagsAsync (IList<UniqueId> uids, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Set the flags of the specified message.
		/// </summary>
		/// <remarks>
		/// Sets the flags of the specified message.
		/// </remarks>
		/// <param name="uid">The UIDs of the message.</param>
		/// <param name="flags">The message flags to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual void SetFlags (UniqueId uid, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			SetFlags (new [] { uid }, flags, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously set the flags of the specified message.
		/// </summary>
		/// <remarks>
		/// Asynchronously sets the flags of the specified message.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="flags">The message flags to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task SetFlagsAsync (UniqueId uid, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return SetFlagsAsync (new [] { uid }, flags, silent, cancellationToken);
		}

		/// <summary>
		/// Set the flags of the specified message.
		/// </summary>
		/// <remarks>
		/// Sets the flags of the specified message.
		/// </remarks>
		/// <param name="uid">The UIDs of the message.</param>
		/// <param name="flags">The message flags to set.</param>
		/// <param name="keywords">A set of user-defined flags to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual void SetFlags (UniqueId uid, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			SetFlags (new [] { uid }, flags, keywords, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously set the flags of the specified message.
		/// </summary>
		/// <remarks>
		/// Asynchronously sets the flags of the specified message.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="flags">The message flags to set.</param>
		/// <param name="keywords">A set of user-defined flags to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task SetFlagsAsync (UniqueId uid, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return SetFlagsAsync (new [] { uid }, flags, keywords, silent, cancellationToken);
		}

		/// <summary>
		/// Set the flags of the specified messages.
		/// </summary>
		/// <remarks>
		/// Sets the flags of the specified messages.
		/// </remarks>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="flags">The message flags to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="uids"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual void SetFlags (IList<UniqueId> uids, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			SetFlags (uids, flags, null, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously set the flags of the specified messages.
		/// </summary>
		/// <remarks>
		/// Asynchronously sets the flags of the specified messages.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="flags">The message flags to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="uids"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task SetFlagsAsync (IList<UniqueId> uids, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return SetFlagsAsync (uids, flags, null, silent, cancellationToken);
		}

		/// <summary>
		/// Set the flags of the specified messages.
		/// </summary>
		/// <remarks>
		/// Sets the flags of the specified messages.
		/// </remarks>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="flags">The message flags to set.</param>
		/// <param name="keywords">A set of user-defined flags to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="uids"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void SetFlags (IList<UniqueId> uids, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously set the flags of the specified messages.
		/// </summary>
		/// <remarks>
		/// Asynchronously sets the flags of the specified messages.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="flags">The message flags to set.</param>
		/// <param name="keywords">A set of user-defined flags to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="uids"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task SetFlagsAsync (IList<UniqueId> uids, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Add a set of flags to the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Adds a set of flags to the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The unique IDs of the messages that were not updated.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="flags">The message flags to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual IList<UniqueId> AddFlags (IList<UniqueId> uids, ulong modseq, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return AddFlags (uids, modseq, flags, null, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously add a set of flags to the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Asynchronously adds a set of flags to the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The unique IDs of the messages that were not updated.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="flags">The message flags to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task<IList<UniqueId>> AddFlagsAsync (IList<UniqueId> uids, ulong modseq, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return AddFlagsAsync (uids, modseq, flags, null, silent, cancellationToken);
		}

		/// <summary>
		/// Add a set of flags to the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Adds a set of flags to the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The unique IDs of the messages that were not updated.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="flags">The message flags to add.</param>
		/// <param name="keywords">A set of user-defined flags to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<UniqueId> AddFlags (IList<UniqueId> uids, ulong modseq, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously add a set of flags to the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Asynchronously adds a set of flags to the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The unique IDs of the messages that were not updated.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="flags">The message flags to add.</param>
		/// <param name="keywords">A set of user-defined flags to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<UniqueId>> AddFlagsAsync (IList<UniqueId> uids, ulong modseq, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Remove a set of flags from the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Removes a set of flags from the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The unique IDs of the messages that were not updated.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="flags">The message flags to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual IList<UniqueId> RemoveFlags (IList<UniqueId> uids, ulong modseq, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return RemoveFlags (uids, modseq, flags, null, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously remove a set of flags from the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Asynchronously removes a set of flags from the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The unique IDs of the messages that were not updated.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="flags">The message flags to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task<IList<UniqueId>> RemoveFlagsAsync (IList<UniqueId> uids, ulong modseq, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return RemoveFlagsAsync (uids, modseq, flags, null, silent, cancellationToken);
		}

		/// <summary>
		/// Remove a set of flags from the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Removes a set of flags from the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The unique IDs of the messages that were not updated.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="flags">The message flags to remove.</param>
		/// <param name="keywords">A set of user-defined flags to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<UniqueId> RemoveFlags (IList<UniqueId> uids, ulong modseq, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously remove a set of flags from the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Asynchronously removes a set of flags from the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The unique IDs of the messages that were not updated.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="flags">The message flags to remove.</param>
		/// <param name="keywords">A set of user-defined flags to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<UniqueId>> RemoveFlagsAsync (IList<UniqueId> uids, ulong modseq, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Set the flags of the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Sets the flags of the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The unique IDs of the messages that were not updated.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="flags">The message flags to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="uids"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual IList<UniqueId> SetFlags (IList<UniqueId> uids, ulong modseq, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return SetFlags (uids, modseq, flags, null, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously set the flags of the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Asynchronously sets the flags of the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The unique IDs of the messages that were not updated.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="flags">The message flags to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="uids"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task<IList<UniqueId>> SetFlagsAsync (IList<UniqueId> uids, ulong modseq, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return SetFlagsAsync (uids, modseq, flags, null, silent, cancellationToken);
		}

		/// <summary>
		/// Set the flags of the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Sets the flags of the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The unique IDs of the messages that were not updated.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="flags">The message flags to set.</param>
		/// <param name="keywords">A set of user-defined flags to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="uids"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<UniqueId> SetFlags (IList<UniqueId> uids, ulong modseq, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously set the flags of the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Asynchronously sets the flags of the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The unique IDs of the messages that were not updated.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="flags">The message flags to set.</param>
		/// <param name="keywords">A set of user-defined flags to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="uids"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="uids"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<UniqueId>> SetFlagsAsync (IList<UniqueId> uids, ulong modseq, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Add a set of flags to the specified message.
		/// </summary>
		/// <remarks>
		/// Adds a set of flags to the specified message.
		/// </remarks>
		/// <param name="index">The index of the message.</param>
		/// <param name="flags">The message flags to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="index"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual void AddFlags (int index, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			AddFlags (new [] { index }, flags, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously add a set of flags to the specified message.
		/// </summary>
		/// <remarks>
		/// Asynchronously adds a set of flags to the specified message.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="index">The index of the messages.</param>
		/// <param name="flags">The message flags to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="index"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task AddFlagsAsync (int index, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return AddFlagsAsync (new [] { index }, flags, silent, cancellationToken);
		}

		/// <summary>
		/// Add a set of flags to the specified message.
		/// </summary>
		/// <remarks>
		/// Adds a set of flags to the specified message.
		/// </remarks>
		/// <param name="index">The index of the message.</param>
		/// <param name="flags">The message flags to add.</param>
		/// <param name="keywords">A set of user-defined flags to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="index"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual void AddFlags (int index, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			AddFlags (new [] { index }, flags, keywords, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously add a set of flags to the specified message.
		/// </summary>
		/// <remarks>
		/// Asynchronously adds a set of flags to the specified message.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="index">The index of the messages.</param>
		/// <param name="flags">The message flags to add.</param>
		/// <param name="keywords">A set of user-defined flags to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="index"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task AddFlagsAsync (int index, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return AddFlagsAsync (new [] { index }, flags, keywords, silent, cancellationToken);
		}

		/// <summary>
		/// Add a set of flags to the specified messages.
		/// </summary>
		/// <remarks>
		/// Adds a set of flags to the specified messages.
		/// </remarks>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="flags">The message flags to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="indexes"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual void AddFlags (IList<int> indexes, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			AddFlags (indexes, flags, null, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously add a set of flags to the specified messages.
		/// </summary>
		/// <remarks>
		/// Asynchronously adds a set of flags to the specified messages.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="flags">The message flags to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="indexes"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task AddFlagsAsync (IList<int> indexes, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return AddFlagsAsync (indexes, flags, null, silent, cancellationToken);
		}

		/// <summary>
		/// Add a set of flags to the specified messages.
		/// </summary>
		/// <remarks>
		/// Adds a set of flags to the specified messages.
		/// </remarks>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="flags">The message flags to add.</param>
		/// <param name="keywords">A set of user-defined flags to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="indexes"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void AddFlags (IList<int> indexes, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously add a set of flags to the specified messages.
		/// </summary>
		/// <remarks>
		/// Asynchronously adds a set of flags to the specified messages.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="flags">The message flags to add.</param>
		/// <param name="keywords">A set of user-defined flags to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="indexes"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task AddFlagsAsync (IList<int> indexes, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Remove a set of flags from the specified message.
		/// </summary>
		/// <remarks>
		/// Removes a set of flags from the specified message.
		/// </remarks>
		/// <param name="index">The index of the message.</param>
		/// <param name="flags">The message flags to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="index"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual void RemoveFlags (int index, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			RemoveFlags (new [] { index }, flags, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously remove a set of flags from the specified message.
		/// </summary>
		/// <remarks>
		/// Asynchronously removes a set of flags from the specified message.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="index">The index of the message.</param>
		/// <param name="flags">The message flags to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="index"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task RemoveFlagsAsync (int index, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return RemoveFlagsAsync (new [] { index }, flags, silent, cancellationToken);
		}

		/// <summary>
		/// Remove a set of flags from the specified message.
		/// </summary>
		/// <remarks>
		/// Removes a set of flags from the specified message.
		/// </remarks>
		/// <param name="index">The index of the message.</param>
		/// <param name="flags">The message flags to remove.</param>
		/// <param name="keywords">A set of user-defined flags to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="index"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual void RemoveFlags (int index, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			RemoveFlags (new [] { index }, flags, keywords, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously remove a set of flags from the specified message.
		/// </summary>
		/// <remarks>
		/// Asynchronously removes a set of flags from the specified message.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="index">The index of the message.</param>
		/// <param name="flags">The message flags to remove.</param>
		/// <param name="keywords">A set of user-defined flags to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="index"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task RemoveFlagsAsync (int index, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return RemoveFlagsAsync (new [] { index }, flags, keywords, silent, cancellationToken);
		}

		/// <summary>
		/// Remove a set of flags from the specified messages.
		/// </summary>
		/// <remarks>
		/// Removes a set of flags from the specified messages.
		/// </remarks>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="flags">The message flags to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="indexes"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual void RemoveFlags (IList<int> indexes, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			RemoveFlags (indexes, flags, null, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously remove a set of flags from the specified messages.
		/// </summary>
		/// <remarks>
		/// Asynchronously removes a set of flags from the specified messages.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="flags">The message flags to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="indexes"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task RemoveFlagsAsync (IList<int> indexes, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return RemoveFlagsAsync (indexes, flags, null, silent, cancellationToken);
		}

		/// <summary>
		/// Remove a set of flags from the specified messages.
		/// </summary>
		/// <remarks>
		/// Removes a set of flags from the specified messages.
		/// </remarks>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="flags">The message flags to remove.</param>
		/// <param name="keywords">A set of user-defined flags to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="indexes"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void RemoveFlags (IList<int> indexes, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously remove a set of flags from the specified messages.
		/// </summary>
		/// <remarks>
		/// Asynchronously removes a set of flags from the specified messages.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="flags">The message flags to remove.</param>
		/// <param name="keywords">A set of user-defined flags to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="indexes"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task RemoveFlagsAsync (IList<int> indexes, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Set the flags of the specified message.
		/// </summary>
		/// <remarks>
		/// Sets the flags of the specified message.
		/// </remarks>
		/// <param name="index">The index of the message.</param>
		/// <param name="flags">The message flags to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="index"/> is invalid.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual void SetFlags (int index, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			SetFlags (new [] { index }, flags, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously set the flags of the specified message.
		/// </summary>
		/// <remarks>
		/// Asynchronously sets the flags of the specified message.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="index">The index of the message.</param>
		/// <param name="flags">The message flags to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="index"/> is invalid.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task SetFlagsAsync (int index, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return SetFlagsAsync (new [] { index }, flags, silent, cancellationToken);
		}

		/// <summary>
		/// Set the flags of the specified message.
		/// </summary>
		/// <remarks>
		/// Sets the flags of the specified message.
		/// </remarks>
		/// <param name="index">The index of the message.</param>
		/// <param name="flags">The message flags to set.</param>
		/// <param name="keywords">A set of user-defined flags to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="index"/> is invalid.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual void SetFlags (int index, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			SetFlags (new [] { index }, flags, keywords, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously set the flags of the specified message.
		/// </summary>
		/// <remarks>
		/// Asynchronously sets the flags of the specified message.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="index">The index of the message.</param>
		/// <param name="flags">The message flags to set.</param>
		/// <param name="keywords">A set of user-defined flags to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="index"/> is invalid.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task SetFlagsAsync (int index, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return SetFlagsAsync (new [] { index }, flags, keywords, silent, cancellationToken);
		}

		/// <summary>
		/// Set the flags of the specified messages.
		/// </summary>
		/// <remarks>
		/// Sets the flags of the specified messages.
		/// </remarks>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="flags">The message flags to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="indexes"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="indexes"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual void SetFlags (IList<int> indexes, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			SetFlags (indexes, flags, null, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously set the flags of the specified messages.
		/// </summary>
		/// <remarks>
		/// Asynchronously sets the flags of the specified messages.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="flags">The message flags to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="indexes"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="indexes"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task SetFlagsAsync (IList<int> indexes, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return SetFlagsAsync (indexes, flags, null, silent, cancellationToken);
		}

		/// <summary>
		/// Set the flags of the specified messages.
		/// </summary>
		/// <remarks>
		/// Sets the flags of the specified messages.
		/// </remarks>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="flags">The message flags to set.</param>
		/// <param name="keywords">A set of user-defined flags to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="indexes"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="indexes"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void SetFlags (IList<int> indexes, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously set the flags of the specified messages.
		/// </summary>
		/// <remarks>
		/// Asynchronously sets the flags of the specified messages.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="flags">The message flags to set.</param>
		/// <param name="keywords">A set of user-defined flags to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="indexes"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="indexes"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task SetFlagsAsync (IList<int> indexes, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Add a set of flags to the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Adds a set of flags to the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The indexes of the messages that were not updated.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="flags">The message flags to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="indexes"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual IList<int> AddFlags (IList<int> indexes, ulong modseq, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return AddFlags (indexes, modseq, flags, null, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously add a set of flags to the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Asynchronously adds a set of flags to the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The indexes of the messages that were not updated.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="flags">The message flags to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="indexes"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task<IList<int>> AddFlagsAsync (IList<int> indexes, ulong modseq, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return AddFlagsAsync (indexes, modseq, flags, null, silent, cancellationToken);
		}

		/// <summary>
		/// Add a set of flags to the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Adds a set of flags to the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The indexes of the messages that were not updated.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="flags">The message flags to add.</param>
		/// <param name="keywords">A set of user-defined flags to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="indexes"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<int> AddFlags (IList<int> indexes, ulong modseq, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously add a set of flags to the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Asynchronously adds a set of flags to the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The indexes of the messages that were not updated.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="flags">The message flags to add.</param>
		/// <param name="keywords">A set of user-defined flags to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="indexes"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<int>> AddFlagsAsync (IList<int> indexes, ulong modseq, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Remove a set of flags from the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Removes a set of flags from the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The indexes of the messages that were not updated.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="flags">The message flags to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="indexes"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual IList<int> RemoveFlags (IList<int> indexes, ulong modseq, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return RemoveFlags (indexes, modseq, flags, null, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously remove a set of flags from the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Asynchronously removes a set of flags from the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The indexes of the messages that were not updated.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="flags">The message flags to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="indexes"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task<IList<int>> RemoveFlagsAsync (IList<int> indexes, ulong modseq, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return RemoveFlagsAsync (indexes, modseq, flags, null, silent, cancellationToken);
		}

		/// <summary>
		/// Remove a set of flags from the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Removes a set of flags from the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The indexes of the messages that were not updated.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="flags">The message flags to remove.</param>
		/// <param name="keywords">A set of user-defined flags to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="indexes"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<int> RemoveFlags (IList<int> indexes, ulong modseq, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously remove a set of flags from the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Asynchronously removes a set of flags from the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The indexes of the messages that were not updated.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="flags">The message flags to remove.</param>
		/// <param name="keywords">A set of user-defined flags to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="indexes"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No flags were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<int>> RemoveFlagsAsync (IList<int> indexes, ulong modseq, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Set the flags of the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Sets the flags of the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The indexes of the messages that were not updated.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="flags">The message flags to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="indexes"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="indexes"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual IList<int> SetFlags (IList<int> indexes, ulong modseq, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return SetFlags (indexes, modseq, flags, null, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously set the flags of the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Asynchronously sets the flags of the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The indexes of the messages that were not updated.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="flags">The message flags to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="indexes"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="indexes"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task<IList<int>> SetFlagsAsync (IList<int> indexes, ulong modseq, MessageFlags flags, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return SetFlagsAsync (indexes, modseq, flags, null, silent, cancellationToken);
		}

		/// <summary>
		/// Set the flags of the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Sets the flags of the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The indexes of the messages that were not updated.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="flags">The message flags to set.</param>
		/// <param name="keywords">A set of user-defined flags to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="indexes"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="indexes"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<int> SetFlags (IList<int> indexes, ulong modseq, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously set the flags of the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Asynchronously sets the flags of the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The indexes of the messages that were not updated.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="flags">The message flags to set.</param>
		/// <param name="keywords">A set of user-defined flags to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageFlagsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="indexes"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="indexes"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<int>> SetFlagsAsync (IList<int> indexes, ulong modseq, MessageFlags flags, HashSet<string> keywords, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Add a set of labels to the specified message.
		/// </summary>
		/// <remarks>
		/// Adds a set of labels to the specified message.
		/// </remarks>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="labels">The labels to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="labels"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="uid"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No labels were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual void AddLabels (UniqueId uid, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			AddLabels (new [] { uid }, labels, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously add a set of labels to the specified message.
		/// </summary>
		/// <remarks>
		/// Asynchronously adds a set of labels to the specified message.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="labels">The labels to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="labels"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="uid"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No labels were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task AddLabelsAsync (UniqueId uid, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return AddLabelsAsync (new [] { uid }, labels, silent, cancellationToken);
		}

		/// <summary>
		/// Add a set of labels to the specified messages.
		/// </summary>
		/// <remarks>
		/// Adds a set of labels to the specified messages.
		/// </remarks>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="labels">The labels to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="labels"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No labels were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void AddLabels (IList<UniqueId> uids, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously add a set of labels to the specified messages.
		/// </summary>
		/// <remarks>
		/// Asynchronously adds a set of labels to the specified messages.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="labels">The labels to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="labels"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No labels were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task AddLabelsAsync (IList<UniqueId> uids, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Remove a set of labels from the specified message.
		/// </summary>
		/// <remarks>
		/// Removes a set of labels from the specified message.
		/// </remarks>
		/// <param name="uid">The UIDs of the message.</param>
		/// <param name="labels">The labels to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="labels"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="uid"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No labels were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual void RemoveLabels (UniqueId uid, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			RemoveLabels (new [] { uid }, labels, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously remove a set of labels from the specified message.
		/// </summary>
		/// <remarks>
		/// Asynchronously removes a set of labels from the specified message.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="labels">The labels to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="labels"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="uid"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No labels were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task RemoveLabelsAsync (UniqueId uid, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return RemoveLabelsAsync (new [] { uid }, labels, silent, cancellationToken);
		}

		/// <summary>
		/// Remove a set of labels from the specified messages.
		/// </summary>
		/// <remarks>
		/// Removes a set of labels from the specified messages.
		/// </remarks>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="labels">The labels to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="labels"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No labels were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void RemoveLabels (IList<UniqueId> uids, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously remove a set of labels from the specified messages.
		/// </summary>
		/// <remarks>
		/// Asynchronously removes a set of labels from the specified messages.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="labels">The labels to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="labels"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No labels were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task RemoveLabelsAsync (IList<UniqueId> uids, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Set the labels of the specified message.
		/// </summary>
		/// <remarks>
		/// Sets the labels of the specified message.
		/// </remarks>
		/// <param name="uid">The UIDs of the message.</param>
		/// <param name="labels">The labels to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="labels"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual void SetLabels (UniqueId uid, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			SetLabels (new [] { uid }, labels, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously set the labels of the specified message.
		/// </summary>
		/// <remarks>
		/// Asynchronously sets the labels of the specified message.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="labels">The labels to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="labels"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task SetLabelsAsync (UniqueId uid, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return SetLabelsAsync (new [] { uid }, labels, silent, cancellationToken);
		}

		/// <summary>
		/// Set the labels of the specified messages.
		/// </summary>
		/// <remarks>
		/// Sets the labels of the specified messages.
		/// </remarks>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="labels">The labels to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="labels"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="uids"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void SetLabels (IList<UniqueId> uids, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously set the labels of the specified messages.
		/// </summary>
		/// <remarks>
		/// Asynchronously sets the labels of the specified messages.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="labels">The labels to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="labels"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="uids"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task SetLabelsAsync (IList<UniqueId> uids, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Add a set of labels to the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Adds a set of labels to the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The unique IDs of the messages that were not updated.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="labels">The labels to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="labels"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="uids"/> is invalid.
		/// <para>-or-</para>
		/// <para>No labels were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<UniqueId> AddLabels (IList<UniqueId> uids, ulong modseq, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously add a set of labels to the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Asynchronously adds a set of labels to the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The unique IDs of the messages that were not updated.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="labels">The labels to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="labels"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No labels were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<UniqueId>> AddLabelsAsync (IList<UniqueId> uids, ulong modseq, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Remove a set of labels from the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Removes a set of labels from the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The unique IDs of the messages that were not updated.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="labels">The labels to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="labels"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No labels were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<UniqueId> RemoveLabels (IList<UniqueId> uids, ulong modseq, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously remove a set of labels from the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Asynchronously removes a set of labels from the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The unique IDs of the messages that were not updated.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="labels">The labels to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="labels"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No labels were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<UniqueId>> RemoveLabelsAsync (IList<UniqueId> uids, ulong modseq, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Set the labels of the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Sets the labels of the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The unique IDs of the messages that were not updated.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="labels">The labels to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="labels"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="uids"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<UniqueId> SetLabels (IList<UniqueId> uids, ulong modseq, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously set the labels of the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Asynchronously sets the labels of the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The unique IDs of the messages that were not updated.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="labels">The labels to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="labels"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="uids"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<UniqueId>> SetLabelsAsync (IList<UniqueId> uids, ulong modseq, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Add a set of labels to the specified message.
		/// </summary>
		/// <remarks>
		/// Adds a set of labels to the specified message.
		/// </remarks>
		/// <param name="index">The index of the message.</param>
		/// <param name="labels">The labels to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="labels"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="index"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No labels were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual void AddLabels (int index, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			AddLabels (new [] { index }, labels, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously add a set of labels to the specified message.
		/// </summary>
		/// <remarks>
		/// Asynchronously adds a set of labels to the specified message.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="index">The index of the messages.</param>
		/// <param name="labels">The labels to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="labels"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="index"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No labels were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task AddLabelsAsync (int index, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return AddLabelsAsync (new [] { index }, labels, silent, cancellationToken);
		}

		/// <summary>
		/// Add a set of labels to the specified messages.
		/// </summary>
		/// <remarks>
		/// Adds a set of labels to the specified messages.
		/// </remarks>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="labels">The labels to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="indexes"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="labels"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No labels were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void AddLabels (IList<int> indexes, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously add a set of labels to the specified messages.
		/// </summary>
		/// <remarks>
		/// Asynchronously adds a set of labels to the specified messages.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="labels">The labels to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="indexes"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="labels"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No labels were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task AddLabelsAsync (IList<int> indexes, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Remove a set of labels from the specified message.
		/// </summary>
		/// <remarks>
		/// Removes a set of labels from the specified message.
		/// </remarks>
		/// <param name="index">The index of the message.</param>
		/// <param name="labels">The labels to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="labels"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="index"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No labels were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual void RemoveLabels (int index, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			RemoveLabels (new [] { index }, labels, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously remove a set of labels from the specified message.
		/// </summary>
		/// <remarks>
		/// Asynchronously removes a set of labels from the specified message.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="index">The index of the message.</param>
		/// <param name="labels">The labels to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="labels"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="index"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No labels were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task RemoveLabelsAsync (int index, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return RemoveLabelsAsync (new [] { index }, labels, silent, cancellationToken);
		}

		/// <summary>
		/// Remove a set of labels from the specified messages.
		/// </summary>
		/// <remarks>
		/// Removes a set of labels from the specified messages.
		/// </remarks>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="labels">The labels to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="indexes"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="labels"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No labels were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void RemoveLabels (IList<int> indexes, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously remove a set of labels from the specified messages.
		/// </summary>
		/// <remarks>
		/// Asynchronously removes a set of labels from the specified messages.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="labels">The labels to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="indexes"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="labels"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No labels were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task RemoveLabelsAsync (IList<int> indexes, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Set the labels of the specified message.
		/// </summary>
		/// <remarks>
		/// Sets the labels of the specified message.
		/// </remarks>
		/// <param name="index">The index of the message.</param>
		/// <param name="labels">The labels to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="labels"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="index"/> is invalid.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual void SetLabels (int index, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			SetLabels (new [] { index }, labels, silent, cancellationToken);
		}

		/// <summary>
		/// Asynchronously set the labels of the specified message.
		/// </summary>
		/// <remarks>
		/// Asynchronously sets the labels of the specified message.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="index">The index of the message.</param>
		/// <param name="labels">The labels to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="labels"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="index"/> is invalid.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task SetLabelsAsync (int index, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken))
		{
			return SetLabelsAsync (new [] { index }, labels, silent, cancellationToken);
		}

		/// <summary>
		/// Set the labels of the specified messages.
		/// </summary>
		/// <remarks>
		/// Sets the labels of the specified messages.
		/// </remarks>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="labels">The labels to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="indexes"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="labels"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="indexes"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void SetLabels (IList<int> indexes, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously set the labels of the specified messages.
		/// </summary>
		/// <remarks>
		/// Asynchronously sets the labels of the specified messages.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="labels">The labels to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="indexes"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="labels"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="indexes"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task SetLabelsAsync (IList<int> indexes, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Add a set of labels to the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Adds a set of labels to the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The indexes of the messages that were not updated.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="labels">The labels to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="indexes"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="labels"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No labels were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<int> AddLabels (IList<int> indexes, ulong modseq, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously add a set of labels to the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Asynchronously adds a set of labels to the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The indexes of the messages that were not updated.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="labels">The labels to add.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="indexes"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="labels"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No labels were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<int>> AddLabelsAsync (IList<int> indexes, ulong modseq, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Remove a set of labels from the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Removes a set of labels from the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The indexes of the messages that were not updated.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="labels">The labels to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="indexes"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="labels"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No labels were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<int> RemoveLabels (IList<int> indexes, ulong modseq, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously remove a set of labels from the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Asynchronously removes a set of labels from the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The indexes of the messages that were not updated.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="labels">The labels to remove.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="indexes"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="labels"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para>One or more of the <paramref name="indexes"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para>No labels were specified.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<int>> RemoveLabelsAsync (IList<int> indexes, ulong modseq, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Set the labels of the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Sets the labels of the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The indexes of the messages that were not updated.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="labels">The labels to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="indexes"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="labels"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="indexes"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<int> SetLabels (IList<int> indexes, ulong modseq, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously set the labels of the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Asynchronously sets the labels of the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The indexes of the messages that were not updated.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="labels">The labels to set.</param>
		/// <param name="silent">If set to <c>true</c>, no <see cref="MessageLabelsChanged"/> events will be emitted.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="indexes"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="labels"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="indexes"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="MailFolder"/> does not support mod-sequences.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<int>> SetLabelsAsync (IList<int> indexes, ulong modseq, IList<string> labels, bool silent, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Store the annotations for the specified message.
		/// </summary>
		/// <remarks>
		/// Stores the annotations for the specified message.
		/// </remarks>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="annotations">The annotations to store.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="annotations"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="IMailFolder"/> is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Cannot store annotations without any properties defined.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="IMailFolder"/> does not support annotations.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual void Store (UniqueId uid, IList<Annotation> annotations, CancellationToken cancellationToken = default (CancellationToken))
		{
			Store (new [] { uid }, annotations, cancellationToken);
		}

		/// <summary>
		/// Asynchronously store the annotations for the specified message.
		/// </summary>
		/// <remarks>
		/// Asynchronously stores the annotations for the specified message.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="uid">The UID of the message.</param>
		/// <param name="annotations">The annotations to store.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="annotations"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="uid"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="IMailFolder"/> is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Cannot store annotations without any properties defined.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="IMailFolder"/> does not support annotations.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task StoreAsync (UniqueId uid, IList<Annotation> annotations, CancellationToken cancellationToken = default (CancellationToken))
		{
			return StoreAsync (new [] { uid }, annotations, cancellationToken);
		}

		/// <summary>
		/// Store the annotations for the specified messages.
		/// </summary>
		/// <remarks>
		/// Stores the annotations for the specified messages.
		/// </remarks>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="annotations">The annotations to store.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="annotations"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="uids"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="IMailFolder"/> is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Cannot store annotations without any properties defined.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="IMailFolder"/> does not support annotations.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void Store (IList<UniqueId> uids, IList<Annotation> annotations, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously store the annotations for the specified messages.
		/// </summary>
		/// <remarks>
		/// Asynchronously stores the annotations for the specified messages.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="annotations">The annotations to store.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="annotations"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="uids"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="IMailFolder"/> is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Cannot store annotations without any properties defined.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="IMailFolder"/> does not support annotations.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task StoreAsync (IList<UniqueId> uids, IList<Annotation> annotations, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Store the annotations for the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Stores the annotations for the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The unique IDs of the messages that were not updated.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="annotations">The annotations to store.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="annotations"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="uids"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="IMailFolder"/> is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Cannot store annotations without any properties defined.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// <para>The <see cref="IMailFolder"/> does not support annotations.</para>
		/// <para>-or-</para>
		/// <para>The <see cref="IMailFolder"/> does not support mod-sequences.</para>
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<UniqueId> Store (IList<UniqueId> uids, ulong modseq, IList<Annotation> annotations, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously store the annotations for the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Asynchronously stores the annotations for the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The unique IDs of the messages that were not updated.</returns>
		/// <param name="uids">The UIDs of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="annotations">The annotations to store.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="annotations"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="uids"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="IMailFolder"/> is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Cannot store annotations without any properties defined.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// <para>The <see cref="IMailFolder"/> does not support annotations.</para>
		/// <para>-or-</para>
		/// <para>The <see cref="IMailFolder"/> does not support mod-sequences.</para>
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<UniqueId>> StoreAsync (IList<UniqueId> uids, ulong modseq, IList<Annotation> annotations, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Store the annotations for the specified message.
		/// </summary>
		/// <remarks>
		/// Stores the annotations for the specified message.
		/// </remarks>
		/// <param name="index">The index of the message.</param>
		/// <param name="annotations">The annotations to store.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="annotations"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="index"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="IMailFolder"/> is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Cannot store annotations without any properties defined.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="IMailFolder"/> does not support annotations.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual void Store (int index, IList<Annotation> annotations, CancellationToken cancellationToken = default (CancellationToken))
		{
			Store (new[] { index }, annotations, cancellationToken);
		}

		/// <summary>
		/// Asynchronously store the annotations for the specified message.
		/// </summary>
		/// <remarks>
		/// Asynchronously stores the annotations for the specified message.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="index">The indexes of the message.</param>
		/// <param name="annotations">The annotations to store.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="annotations"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="index"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="IMailFolder"/> is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Cannot store annotations without any properties defined.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="IMailFolder"/> does not support annotations.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task StoreAsync (int index, IList<Annotation> annotations, CancellationToken cancellationToken = default (CancellationToken))
		{
			return StoreAsync (new [] { index }, annotations, cancellationToken);
		}

		/// <summary>
		/// Store the annotations for the specified messages.
		/// </summary>
		/// <remarks>
		/// Stores the annotations for the specified messages.
		/// </remarks>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="annotations">The annotations to store.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="indexes"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="annotations"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="indexes"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="IMailFolder"/> is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Cannot store annotations without any properties defined.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="IMailFolder"/> does not support annotations.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract void Store (IList<int> indexes, IList<Annotation> annotations, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously store the annotations for the specified messages.
		/// </summary>
		/// <remarks>
		/// Asynchronously stores the annotations for the specified messages.
		/// </remarks>
		/// <returns>An asynchronous task context.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="annotations">The annotations to store.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="indexes"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="annotations"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="indexes"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="IMailFolder"/> is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Cannot store annotations without any properties defined.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// The <see cref="IMailFolder"/> does not support annotations.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task StoreAsync (IList<int> indexes, IList<Annotation> annotations, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Store the annotations for the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Stores the annotations for the specified messages only if their mod-sequence value is less than the specified value.
		/// </remarks>
		/// <returns>The indexes of the messages that were not updated.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="annotations">The annotations to store.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="indexes"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="annotations"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="indexes"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="IMailFolder"/> is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Cannot store annotations without any properties defined.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// <para>The <see cref="IMailFolder"/> does not support annotations.</para>
		/// <para>-or-</para>
		/// <para>The <see cref="IMailFolder"/> does not support mod-sequences.</para>
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<int> Store (IList<int> indexes, ulong modseq, IList<Annotation> annotations, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously store the annotations for the specified messages only if their mod-sequence value is less than the specified value.
		/// </summary>
		/// <remarks>
		/// Asynchronously stores the annotations for the specified messages only if their mod-sequence value is less than the specified value.s
		/// </remarks>
		/// <returns>The indexes of the messages that were not updated.</returns>
		/// <param name="indexes">The indexes of the messages.</param>
		/// <param name="modseq">The mod-sequence value.</param>
		/// <param name="annotations">The annotations to store.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="indexes"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="annotations"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// One or more of the <paramref name="indexes"/> is invalid.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="IMailFolder"/> is not currently open in read-write mode.
		/// </exception>
		/// <exception cref="System.InvalidOperationException">
		/// Cannot store annotations without any properties defined.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// <para>The <see cref="IMailFolder"/> does not support annotations.</para>
		/// <para>-or-</para>
		/// <para>The <see cref="IMailFolder"/> does not support mod-sequences.</para>
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<int>> StoreAsync (IList<int> indexes, ulong modseq, IList<Annotation> annotations, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Search the folder for messages matching the specified query.
		/// </summary>
		/// <remarks>
		/// The returned array of unique identifiers can be used with methods such as
		/// <see cref="IMailFolder.GetMessage(UniqueId,CancellationToken,ITransferProgress)"/>.
		/// </remarks>
		/// <returns>An array of matching UIDs.</returns>
		/// <param name="query">The search query.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="query"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// One or more search terms in the <paramref name="query"/> are not supported by the mail store.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<UniqueId> Search (SearchQuery query, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously search the folder for messages matching the specified query.
		/// </summary>
		/// <remarks>
		/// The returned array of unique identifiers can be used with methods such as
		/// <see cref="IMailFolder.GetMessage(UniqueId,CancellationToken,ITransferProgress)"/>.
		/// </remarks>
		/// <returns>An array of matching UIDs.</returns>
		/// <param name="query">The search query.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="query"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// One or more search terms in the <paramref name="query"/> are not supported by the mail store.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task<IList<UniqueId>> SearchAsync (SearchQuery query, CancellationToken cancellationToken = default (CancellationToken))
		{
			if (query == null)
				throw new ArgumentNullException (nameof (query));

			return Task.Factory.StartNew (() => {
				lock (SyncRoot) {
					return Search (query, cancellationToken);
				}
			}, cancellationToken, TaskCreationOptions.None, TaskScheduler.Default);
		}

		/// <summary>
		/// Search the subset of UIDs in the folder for messages matching the specified query.
		/// </summary>
		/// <remarks>
		/// The returned array of unique identifiers can be used with methods such as
		/// <see cref="IMailFolder.GetMessage(UniqueId,CancellationToken,ITransferProgress)"/>.
		/// </remarks>
		/// <returns>An array of matching UIDs in the specified sort order.</returns>
		/// <param name="uids">The subset of UIDs</param>
		/// <param name="query">The search query.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="query"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="uids"/> is empty.</para>
		/// <para>-or-</para>
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// One or more search terms in the <paramref name="query"/> are not supported by the mail store.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual IList<UniqueId> Search (IList<UniqueId> uids, SearchQuery query, CancellationToken cancellationToken = default (CancellationToken))
		{
			var uidSet = new UidSearchQuery (uids);

			if (query == null)
				throw new ArgumentNullException (nameof (query));

			return Search (uidSet.And (query), cancellationToken);
		}

		/// <summary>
		/// Asynchronously search the subset of UIDs in the folder for messages matching the specified query.
		/// </summary>
		/// <remarks>
		/// The returned array of unique identifiers can be used with methods such as
		/// <see cref="IMailFolder.GetMessage(UniqueId,CancellationToken,ITransferProgress)"/>.
		/// </remarks>
		/// <returns>An array of matching UIDs in the specified sort order.</returns>
		/// <param name="uids">The subset of UIDs</param>
		/// <param name="query">The search query.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="query"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="uids"/> is empty.</para>
		/// <para>-or-</para>
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// One or more search terms in the <paramref name="query"/> are not supported.
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task<IList<UniqueId>> SearchAsync (IList<UniqueId> uids, SearchQuery query, CancellationToken cancellationToken = default (CancellationToken))
		{
			var uidSet = new UidSearchQuery (uids);

			if (query == null)
				throw new ArgumentNullException (nameof (query));

			return SearchAsync (uidSet.And (query), cancellationToken);
		}

		/// <summary>
		/// Search the folder for messages matching the specified query.
		/// </summary>
		/// <remarks>
		/// Searches the folder for messages matching the specified query,
		/// returning only the specified search results.
		/// </remarks>
		/// <returns>The search results.</returns>
		/// <param name="options">The search options.</param>
		/// <param name="query">The search query.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="query"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// <para>One or more search terms in the <paramref name="query"/> are not supported.</para>
		/// <para>-or-</para>
		/// <para>The server does not support the specified search options.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="MailFolder"/> is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract SearchResults Search (SearchOptions options, SearchQuery query, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously search the folder for messages matching the specified query.
		/// </summary>
		/// <remarks>
		/// Asynchronously searches the folder for messages matching the specified query,
		/// returning only the specified search results.
		/// </remarks>
		/// <returns>The search results.</returns>
		/// <param name="options">The search options.</param>
		/// <param name="query">The search query.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="query"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// <para>One or more search terms in the <paramref name="query"/> are not supported.</para>
		/// <para>-or-</para>
		/// <para>The server does not support the specified search options.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="MailFolder"/> is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<SearchResults> SearchAsync (SearchOptions options, SearchQuery query, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Search the subset of UIDs in the folder for messages matching the specified query.
		/// </summary>
		/// <remarks>
		/// Searches the fsubset of UIDs in the folder for messages matching the specified query,
		/// returning only the specified search results.
		/// </remarks>
		/// <returns>The search results.</returns>
		/// <param name="options">The search options.</param>
		/// <param name="uids">The subset of UIDs</param>
		/// <param name="query">The search query.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="query"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="uids"/> is empty.</para>
		/// <para>-or-</para>
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// <para>One or more search terms in the <paramref name="query"/> are not supported.</para>
		/// <para>-or-</para>
		/// <para>The server does not support the specified search options.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual SearchResults Search (SearchOptions options, IList<UniqueId> uids, SearchQuery query, CancellationToken cancellationToken = default (CancellationToken))
		{
			var uidSet = new UidSearchQuery (uids);

			if (query == null)
				throw new ArgumentNullException (nameof (query));

			return Search (options, uidSet.And (query), cancellationToken);
		}

		/// <summary>
		/// Asynchronously search the subset of UIDs in the folder for messages matching the specified query.
		/// </summary>
		/// <remarks>
		/// Asynchronously searches the fsubset of UIDs in the folder for messages matching the specified query,
		/// returning only the specified search results.
		/// </remarks>
		/// <returns>The search results.</returns>
		/// <param name="options">The search options.</param>
		/// <param name="uids">The subset of UIDs</param>
		/// <param name="query">The search query.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="query"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="uids"/> is empty.</para>
		/// <para>-or-</para>
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// <para>One or more search terms in the <paramref name="query"/> are not supported.</para>
		/// <para>-or-</para>
		/// <para>The server does not support the specified search options.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task<SearchResults> SearchAsync (SearchOptions options, IList<UniqueId> uids, SearchQuery query, CancellationToken cancellationToken = default (CancellationToken))
		{
			var uidSet = new UidSearchQuery (uids);

			if (query == null)
				throw new ArgumentNullException (nameof (query));

			return SearchAsync (options, uidSet.And (query), cancellationToken);
		}

		/// <summary>
		/// Sort messages matching the specified query.
		/// </summary>
		/// <remarks>
		/// The returned array of unique identifiers will be sorted in the preferred order and
		/// can be used with <see cref="IMailFolder.GetMessage(UniqueId,CancellationToken,ITransferProgress)"/>.
		/// </remarks>
		/// /// <returns>An array of matching UIDs in the specified sort order.</returns>
		/// <param name="query">The search query.</param>
		/// <param name="orderBy">The sort order.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="query"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="orderBy"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="orderBy"/> is empty.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// <para>One or more search terms in the <paramref name="query"/> are not supported.</para>
		/// <para>-or-</para>
		/// <para>The server does not support sorting search results.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<UniqueId> Sort (SearchQuery query, IList<OrderBy> orderBy, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously sort messages matching the specified query.
		/// </summary>
		/// <remarks>
		/// The returned array of unique identifiers will be sorted in the preferred order and
		/// can be used with <see cref="IMailFolder.GetMessage(UniqueId,CancellationToken,ITransferProgress)"/>.
		/// </remarks>
		/// <returns>An array of matching UIDs in the specified sort order.</returns>
		/// <param name="query">The search query.</param>
		/// <param name="orderBy">The sort order.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="query"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="orderBy"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="orderBy"/> is empty.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// <para>One or more search terms in the <paramref name="query"/> are not supported.</para>
		/// <para>-or-</para>
		/// <para>The server does not support sorting search results.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<UniqueId>> SortAsync (SearchQuery query, IList<OrderBy> orderBy, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Sort messages matching the specified query.
		/// </summary>
		/// <remarks>
		/// The returned array of unique identifiers will be sorted in the preferred order and
		/// can be used with <see cref="IMailFolder.GetMessage(UniqueId,CancellationToken,ITransferProgress)"/>.
		/// </remarks>
		/// <returns>An array of matching UIDs in the specified sort order.</returns>
		/// <param name="uids">The subset of UIDs</param>
		/// <param name="query">The search query.</param>
		/// <param name="orderBy">The sort order.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="query"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="orderBy"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="uids"/> is empty.</para>
		/// <para>-or-</para>
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para><paramref name="orderBy"/> is empty.</para>
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// <para>One or more search terms in the <paramref name="query"/> are not supported.</para>
		/// <para>-or-</para>
		/// <para>The server does not support sorting search results.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual IList<UniqueId> Sort (IList<UniqueId> uids, SearchQuery query, IList<OrderBy> orderBy, CancellationToken cancellationToken = default (CancellationToken))
		{
			var uidSet = new UidSearchQuery (uids);

			if (query == null)
				throw new ArgumentNullException (nameof (query));

			return Sort (uidSet.And (query), orderBy, cancellationToken);
		}

		/// <summary>
		/// Asynchronously sort messages matching the specified query.
		/// </summary>
		/// <remarks>
		/// The returned array of unique identifiers will be sorted in the preferred order and
		/// can be used with <see cref="IMailFolder.GetMessage(UniqueId,CancellationToken,ITransferProgress)"/>.
		/// </remarks>
		/// <returns>An array of matching UIDs in the specified sort order.</returns>
		/// <param name="uids">The subset of UIDs</param>
		/// <param name="query">The search query.</param>
		/// <param name="orderBy">The sort order.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="query"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="orderBy"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="uids"/> is empty.</para>
		/// <para>-or-</para>
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para><paramref name="orderBy"/> is empty.</para>
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// <para>One or more search terms in the <paramref name="query"/> are not supported.</para>
		/// <para>-or-</para>
		/// <para>The server does not support sorting search results.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task<IList<UniqueId>> SortAsync (IList<UniqueId> uids, SearchQuery query, IList<OrderBy> orderBy, CancellationToken cancellationToken = default (CancellationToken))
		{
			var uidSet = new UidSearchQuery (uids);

			if (query == null)
				throw new ArgumentNullException (nameof (query));

			return SortAsync (uidSet.And (query), orderBy, cancellationToken);
		}

		/// <summary>
		/// Sort messages matching the specified query.
		/// </summary>
		/// <remarks>
		/// Searches the folder for messages matching the specified query, returning the search results in the specified sort order.
		/// </remarks>
		/// <returns>The search results.</returns>
		/// <param name="options">The search options.</param>
		/// <param name="query">The search query.</param>
		/// <param name="orderBy">The sort order.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="query"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="orderBy"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="orderBy"/> is empty.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// <para>One or more search terms in the <paramref name="query"/> are not supported.</para>
		/// <para>-or-</para>
		/// <para>The server does not support the specified search options.</para>
		/// <para>-or-</para>
		/// <para>The server does not support sorting search results.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="MailFolder"/> is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract SearchResults Sort (SearchOptions options, SearchQuery query, IList<OrderBy> orderBy, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously sort messages matching the specified query.
		/// </summary>
		/// <remarks>
		/// Asynchronously searches the folder for messages matching the specified query, returning the search results in the specified sort order.
		/// </remarks>
		/// <returns>The search results.</returns>
		/// <param name="options">The search options.</param>
		/// <param name="query">The search query.</param>
		/// <param name="orderBy">The sort order.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="query"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="orderBy"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <paramref name="orderBy"/> is empty.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// <para>One or more search terms in the <paramref name="query"/> are not supported.</para>
		/// <para>-or-</para>
		/// <para>The server does not support the specified search options.</para>
		/// <para>-or-</para>
		/// <para>The server does not support sorting search results.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The <see cref="MailFolder"/> is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<SearchResults> SortAsync (SearchOptions options, SearchQuery query, IList<OrderBy> orderBy, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Sort messages matching the specified query.
		/// </summary>
		/// <remarks>
		/// Searches the folder for messages matching the specified query, returning the search results in the specified sort order.
		/// </remarks>
		/// <returns>The search results.</returns>
		/// <param name="options">The search options.</param>
		/// <param name="uids">The subset of UIDs</param>
		/// <param name="query">The search query.</param>
		/// <param name="orderBy">The sort order.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="query"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="orderBy"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="uids"/> is empty.</para>
		/// <para>-or-</para>
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para><paramref name="orderBy"/> is empty.</para>
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// <para>One or more search terms in the <paramref name="query"/> are not supported.</para>
		/// <para>-or-</para>
		/// <para>The server does not support the specified search options.</para>
		/// <para>-or-</para>
		/// <para>The server does not support sorting search results.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual SearchResults Sort (SearchOptions options, IList<UniqueId> uids, SearchQuery query, IList<OrderBy> orderBy, CancellationToken cancellationToken = default (CancellationToken))
		{
			var uidSet = new UidSearchQuery (uids);

			if (query == null)
				throw new ArgumentNullException (nameof (query));

			return Sort (options, uidSet.And (query), orderBy, cancellationToken);
		}

		/// <summary>
		/// Asynchronously sort messages matching the specified query, returning the search results in the specified sort order.
		/// </summary>
		/// <remarks>
		/// Asynchronously searches the folder for messages matching the specified query,
		/// returning the search results in the specified sort order.
		/// </remarks>
		/// <returns>The search results.</returns>
		/// <param name="options">The search options.</param>
		/// <param name="uids">The subset of UIDs</param>
		/// <param name="query">The search query.</param>
		/// <param name="orderBy">The sort order.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="query"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="orderBy"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="uids"/> is empty.</para>
		/// <para>-or-</para>
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// <para>-or-</para>
		/// <para><paramref name="orderBy"/> is empty.</para>
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// <para>One or more search terms in the <paramref name="query"/> are not supported.</para>
		/// <para>-or-</para>
		/// <para>The server does not support the specified search options.</para>
		/// <para>-or-</para>
		/// <para>The server does not support sorting search results.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public virtual Task<SearchResults> SortAsync (SearchOptions options, IList<UniqueId> uids, SearchQuery query, IList<OrderBy> orderBy, CancellationToken cancellationToken = default (CancellationToken))
		{
			var uidSet = new UidSearchQuery (uids);

			if (query == null)
				throw new ArgumentNullException (nameof (query));

			return SortAsync (options, uidSet.And (query), orderBy, cancellationToken);
		}

		/// <summary>
		/// Thread the messages in the folder that match the search query using the specified threading algorithm.
		/// </summary>
		/// <remarks>
		/// The <see cref="MessageThread.UniqueId"/> can be used with methods such as
		/// <see cref="IMailFolder.GetMessage(UniqueId,CancellationToken,ITransferProgress)"/>.
		/// </remarks>
		/// <returns>An array of message threads.</returns>
		/// <param name="algorithm">The threading algorithm to use.</param>
		/// <param name="query">The search query.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="algorithm"/> is not supported.
		/// </exception>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="query"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// <para>One or more search terms in the <paramref name="query"/> are not supported.</para>
		/// <para>-or-</para>
		/// <para>The server does not support threading search results.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<MessageThread> Thread (ThreadingAlgorithm algorithm, SearchQuery query, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously thread the messages in the folder that match the search query using the specified threading algorithm.
		/// </summary>
		/// <remarks>
		/// The <see cref="MessageThread.UniqueId"/> can be used with methods such as
		/// <see cref="IMailFolder.GetMessage(UniqueId,CancellationToken,ITransferProgress)"/>.
		/// </remarks>
		/// <returns>An array of message threads.</returns>
		/// <param name="algorithm">The threading algorithm to use.</param>
		/// <param name="query">The search query.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="algorithm"/> is not supported.
		/// </exception>
		/// <exception cref="System.ArgumentNullException">
		/// <paramref name="query"/> is <c>null</c>.
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// <para>One or more search terms in the <paramref name="query"/> are not supported.</para>
		/// <para>-or-</para>
		/// <para>The server does not support threading search results.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<MessageThread>> ThreadAsync (ThreadingAlgorithm algorithm, SearchQuery query, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Thread the messages in the folder that match the search query using the specified threading algorithm.
		/// </summary>
		/// <remarks>
		/// The <see cref="MessageThread.UniqueId"/> can be used with methods such as
		/// <see cref="IMailFolder.GetMessage(UniqueId,CancellationToken,ITransferProgress)"/>.
		/// </remarks>
		/// <returns>An array of message threads.</returns>
		/// <param name="uids">The subset of UIDs</param>
		/// <param name="algorithm">The threading algorithm to use.</param>
		/// <param name="query">The search query.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="algorithm"/> is not supported.
		/// </exception>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="query"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="uids"/> is empty.</para>
		/// <para>-or-</para>
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// <para>One or more search terms in the <paramref name="query"/> are not supported.</para>
		/// <para>-or-</para>
		/// <para>The server does not support threading search results.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract IList<MessageThread> Thread (IList<UniqueId> uids, ThreadingAlgorithm algorithm, SearchQuery query, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Asynchronously thread the messages in the folder that match the search query using the specified threading algorithm.
		/// </summary>
		/// <remarks>
		/// The <see cref="MessageThread.UniqueId"/> can be used with methods such as
		/// <see cref="IMailFolder.GetMessage(UniqueId,CancellationToken,ITransferProgress)"/>.
		/// </remarks>
		/// <returns>An array of message threads.</returns>
		/// <param name="uids">The subset of UIDs</param>
		/// <param name="algorithm">The threading algorithm to use.</param>
		/// <param name="query">The search query.</param>
		/// <param name="cancellationToken">The cancellation token.</param>
		/// <exception cref="System.ArgumentOutOfRangeException">
		/// <paramref name="algorithm"/> is not supported.
		/// </exception>
		/// <exception cref="System.ArgumentNullException">
		/// <para><paramref name="uids"/> is <c>null</c>.</para>
		/// <para>-or-</para>
		/// <para><paramref name="query"/> is <c>null</c>.</para>
		/// </exception>
		/// <exception cref="System.ArgumentException">
		/// <para><paramref name="uids"/> is empty.</para>
		/// <para>-or-</para>
		/// <para>One or more of the <paramref name="uids"/> is invalid.</para>
		/// </exception>
		/// <exception cref="System.NotSupportedException">
		/// <para>One or more search terms in the <paramref name="query"/> are not supported.</para>
		/// <para>-or-</para>
		/// <para>The server does not support threading search results.</para>
		/// </exception>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		/// <exception cref="System.OperationCanceledException">
		/// The operation was canceled via the cancellation token.
		/// </exception>
		/// <exception cref="System.IO.IOException">
		/// An I/O error occurred.
		/// </exception>
		/// <exception cref="ProtocolException">
		/// The server's response contained unexpected tokens.
		/// </exception>
		/// <exception cref="CommandException">
		/// The command failed.
		/// </exception>
		public abstract Task<IList<MessageThread>> ThreadAsync (IList<UniqueId> uids, ThreadingAlgorithm algorithm, SearchQuery query, CancellationToken cancellationToken = default (CancellationToken));

		/// <summary>
		/// Occurs when the folder is opened.
		/// </summary>
		/// <remarks>
		/// The <see cref="Opened"/> event is emitted when the folder is opened.
		/// </remarks>
		public event EventHandler<EventArgs> Opened;

		/// <summary>
		/// Raise the opened event.
		/// </summary>
		/// <remarks>
		/// Raises the opened event.
		/// </remarks>
		protected virtual void OnOpened ()
		{
			Opened?.Invoke (this, EventArgs.Empty);
		}

		/// <summary>
		/// Occurs when the folder is closed.
		/// </summary>
		/// <remarks>
		/// The <see cref="Closed"/> event is emitted when the folder is closed.
		/// </remarks>
		public event EventHandler<EventArgs> Closed;

		/// <summary>
		/// Raise the closed event.
		/// </summary>
		/// <remarks>
		/// Raises the closed event.
		/// </remarks>
		internal protected virtual void OnClosed ()
		{
			PermanentFlags = MessageFlags.None;
			AcceptedFlags = MessageFlags.None;
			Access = FolderAccess.None;

			AnnotationAccess = AnnotationAccess.None;
			AnnotationScopes = AnnotationScope.None;
			MaxAnnotationSize = 0;

			Closed?.Invoke (this, EventArgs.Empty);
		}

		/// <summary>
		/// Occurs when the folder is deleted.
		/// </summary>
		/// <remarks>
		/// The <see cref="Deleted"/> event is emitted when the folder is deleted.
		/// </remarks>
		public event EventHandler<EventArgs> Deleted;

		/// <summary>
		/// Raise the deleted event.
		/// </summary>
		/// <remarks>
		/// Raises the deleted event.
		/// </remarks>
		protected virtual void OnDeleted ()
		{
			Deleted?.Invoke (this, EventArgs.Empty);
		}

		/// <summary>
		/// Occurs when the folder is renamed.
		/// </summary>
		/// <remarks>
		/// The <see cref="Renamed"/> event is emitted when the folder is renamed.
		/// </remarks>
		public event EventHandler<FolderRenamedEventArgs> Renamed;

		/// <summary>
		/// Raise the renamed event.
		/// </summary>
		/// <remarks>
		/// Raises the renamed event.
		/// </remarks>
		/// <param name="oldName">The old name of the folder.</param>
		/// <param name="newName">The new name of the folder.</param>
		protected virtual void OnRenamed (string oldName, string newName)
		{
			Renamed?.Invoke (this, new FolderRenamedEventArgs (oldName, newName));
		}

		/// <summary>
		/// Notifies the folder that a parent folder has been renamed.
		/// </summary>
		/// <remarks>
		/// <see cref="IMailFolder"/> implementations should override this method
		/// to update their state (such as updating their <see cref="FullName"/>
		/// property).
		/// </remarks>
		protected virtual void OnParentFolderRenamed ()
		{
		}

		void OnParentFolderRenamed (object sender, FolderRenamedEventArgs e)
		{
			var oldFullName = FullName;

			OnParentFolderRenamed ();

			if (FullName != oldFullName)
				OnRenamed (oldFullName, FullName);
		}

		/// <summary>
		/// Occurs when the folder is subscribed.
		/// </summary>
		/// <remarks>
		/// The <see cref="Subscribed"/> event is emitted when the folder is subscribed.
		/// </remarks>
		public event EventHandler<EventArgs> Subscribed;

		/// <summary>
		/// Raise the subscribed event.
		/// </summary>
		/// <remarks>
		/// Raises the subscribed event.
		/// </remarks>
		protected virtual void OnSubscribed ()
		{
			Subscribed?.Invoke (this, EventArgs.Empty);
		}

		/// <summary>
		/// Occurs when the folder is unsubscribed.
		/// </summary>
		/// <remarks>
		/// The <see cref="Unsubscribed"/> event is emitted when the folder is unsubscribed.
		/// </remarks>
		public event EventHandler<EventArgs> Unsubscribed;

		/// <summary>
		/// Raise the unsubscribed event.
		/// </summary>
		/// <remarks>
		/// Raises the unsubscribed event.
		/// </remarks>
		protected virtual void OnUnsubscribed ()
		{
			Unsubscribed?.Invoke (this, EventArgs.Empty);
		}

		/// <summary>
		/// Occurs when a message is expunged from the folder.
		/// </summary>
		/// <remarks>
		/// The <see cref="MessageExpunged"/> event is emitted when a message is expunged from the folder.
		/// </remarks>
		/// <example>
		/// <code language="c#" source="Examples\ImapIdleExample.cs"/>
		/// </example>
		public event EventHandler<MessageEventArgs> MessageExpunged;

		/// <summary>
		/// Raise the message expunged event.
		/// </summary>
		/// <remarks>
		/// Raises the message expunged event.
		/// </remarks>
		/// <param name="args">The message expunged event args.</param>
		protected virtual void OnMessageExpunged (MessageEventArgs args)
		{
			MessageExpunged?.Invoke (this, args);
		}

		/// <summary>
		/// Occurs when a message vanishes from the folder.
		/// </summary>
		/// <remarks>
		/// The <see cref="MessagesVanished"/> event is emitted when messages vanish from the folder.
		/// </remarks>
		public event EventHandler<MessagesVanishedEventArgs> MessagesVanished;

		/// <summary>
		/// Raise the messages vanished event.
		/// </summary>
		/// <remarks>
		/// Raises the messages vanished event.
		/// </remarks>
		/// <param name="args">The messages vanished event args.</param>
		protected virtual void OnMessagesVanished (MessagesVanishedEventArgs args)
		{
			MessagesVanished?.Invoke (this, args);
		}

		/// <summary>
		/// Occurs when flags changed on a message.
		/// </summary>
		/// <remarks>
		/// The <see cref="MessageFlagsChanged"/> event is emitted when the flags for a message are changed.
		/// </remarks>
		/// <example>
		/// <code language="c#" source="Examples\ImapIdleExample.cs"/>
		/// </example>
		public event EventHandler<MessageFlagsChangedEventArgs> MessageFlagsChanged;

		/// <summary>
		/// Raise the message flags changed event.
		/// </summary>
		/// <remarks>
		/// Raises the message flags changed event.
		/// </remarks>
		/// <param name="args">The message flags changed event args.</param>
		protected virtual void OnMessageFlagsChanged (MessageFlagsChangedEventArgs args)
		{
			MessageFlagsChanged?.Invoke (this, args);
		}

		/// <summary>
		/// Occurs when labels changed on a message.
		/// </summary>
		/// <remarks>
		/// The <see cref="MessageLabelsChanged"/> event is emitted when the labels for a message are changed.
		/// </remarks>
		public event EventHandler<MessageLabelsChangedEventArgs> MessageLabelsChanged;

		/// <summary>
		/// Raise the message labels changed event.
		/// </summary>
		/// <remarks>
		/// Raises the message labels changed event.
		/// </remarks>
		/// <param name="args">The message labels changed event args.</param>
		protected virtual void OnMessageLabelsChanged (MessageLabelsChangedEventArgs args)
		{
			MessageLabelsChanged?.Invoke (this, args);
		}

		/// <summary>
		/// Occurs when annotations changed on a message.
		/// </summary>
		/// <remarks>
		/// The <see cref="AnnotationsChanged"/> event is emitted when the annotations for a message are changed.
		/// </remarks>
		public event EventHandler<AnnotationsChangedEventArgs> AnnotationsChanged;

		/// <summary>
		/// Raise the message annotations changed event.
		/// </summary>
		/// <remarks>
		/// Raises the message annotations changed event.
		/// </remarks>
		/// <param name="args">The message annotations changed event args.</param>
		protected virtual void OnAnnotationsChanged (AnnotationsChangedEventArgs args)
		{
			AnnotationsChanged?.Invoke (this, args);
		}

		/// <summary>
		/// Occurs when a message summary is fetched from the folder.
		/// </summary>
		/// <remarks>
		/// <para>Emitted when a message summary is fetched from the folder.</para>
		/// <para>When multiple message summaries are being fetched from a remote folder,
		/// it is possible that the connection will drop or some other exception will
		/// occur, causing the Fetch method to fail and lose all of the data that has been
		/// downloaded up to that point, requiring the client to request the same set of
		/// message summaries all over again after it reconnects. This is obviously
		/// inefficient. To alleviate this potential problem, this event will be emitted
		/// as soon as the <see cref="IMailFolder"/> successfully parses each untagged FETCH
		/// response from the server, allowing the client to commit this data immediately to
		/// its local cache.</para>
		/// <note type="note">Depending on the IMAP server, it is possible that the
		/// <see cref="MessageSummaryFetched"/> event will be emitted for the same message
		/// multiple times if the IMAP server happens to split the requested fields into
		/// multiple untagged FETCH responses. Use the <see cref="IMessageSummary.Fields"/>
		/// property to determine which f<see cref="IMessageSummary"/> properties have
		/// been populated.</note>
		/// </remarks>
		public event EventHandler<MessageSummaryFetchedEventArgs> MessageSummaryFetched;

		/// <summary>
		/// Raise the message summary fetched event.
		/// </summary>
		/// <remarks>
		/// <para>Raises the message summary fetched event.</para>
		/// <para>When multiple message summaries are being fetched from a remote folder,
		/// it is possible that the connection will drop or some other exception will
		/// occur, causing the Fetch method to fail and lose all of the data that has been
		/// downloaded up to that point, requiring the client to request the same set of
		/// message summaries all over again after it reconnects. This is obviously
		/// inefficient. To alleviate this potential problem, this event will be emitted
		/// as soon as the <see cref="IMailFolder"/> successfully parses each untagged FETCH
		/// response from the server, allowing the client to commit this data immediately to
		/// its local cache.</para>
		/// <note type="note">Depending on the IMAP server, it is possible that
		/// <see cref="OnMessageSummaryFetched"/> will be invoked for the same message
		/// multiple times if the IMAP server happens to split the requested fields into
		/// multiple untagged FETCH responses. Use the <see cref="IMessageSummary.Fields"/>
		/// property to determine which f<see cref="IMessageSummary"/> properties have
		/// been populated.</note>
		/// </remarks>
		/// <param name="message">The message summary.</param>
		protected virtual void OnMessageSummaryFetched (IMessageSummary message)
		{
			MessageSummaryFetched?.Invoke (this, new MessageSummaryFetchedEventArgs (message));
		}

		/// <summary>
		/// Occurs when metadata changes.
		/// </summary>
		/// <remarks>
		/// The <see cref="MetadataChanged"/> event is emitted when metadata changes.
		/// </remarks>
		public event EventHandler<MetadataChangedEventArgs> MetadataChanged;

		/// <summary>
		/// Raise the metadata changed event.
		/// </summary>
		/// <remarks>
		/// Raises the metadata changed event.
		/// </remarks>
		/// <param name="metadata">The metadata that changed.</param>
		internal protected virtual void OnMetadataChanged (Metadata metadata)
		{
			MetadataChanged?.Invoke (this, new MetadataChangedEventArgs (metadata));
		}

		/// <summary>
		/// Occurs when the mod-sequence changed on a message.
		/// </summary>
		/// <remarks>
		/// The <see cref="ModSeqChanged"/> event is emitted when the mod-sequence for a message is changed.
		/// </remarks>
		public event EventHandler<ModSeqChangedEventArgs> ModSeqChanged;

		/// <summary>
		/// Raise the message mod-sequence changed event.
		/// </summary>
		/// <remarks>
		/// Raises the message mod-sequence changed event.
		/// </remarks>
		/// <param name="args">The mod-sequence changed event args.</param>
		protected virtual void OnModSeqChanged (ModSeqChangedEventArgs args)
		{
			ModSeqChanged?.Invoke (this, args);
		}

		/// <summary>
		/// Occurs when the highest mod-sequence changes.
		/// </summary>
		/// <remarks>
		/// The <see cref="HighestModSeqChanged"/> event is emitted whenever the <see cref="HighestModSeq"/> value changes.
		/// </remarks>
		public event EventHandler<EventArgs> HighestModSeqChanged;

		/// <summary>
		/// Raise the highest mod-sequence changed event.
		/// </summary>
		/// <remarks>
		/// Raises the highest mod-sequence changed event.
		/// </remarks>
		protected virtual void OnHighestModSeqChanged ()
		{
			HighestModSeqChanged?.Invoke (this, EventArgs.Empty);
		}

		/// <summary>
		/// Occurs when the next UID changes.
		/// </summary>
		/// <remarks>
		/// The <see cref="UidNextChanged"/> event is emitted whenever the <see cref="UidNext"/> value changes.
		/// </remarks>
		public event EventHandler<EventArgs> UidNextChanged;

		/// <summary>
		/// Raise the next UID changed event.
		/// </summary>
		/// <remarks>
		/// Raises the next UID changed event.
		/// </remarks>
		protected virtual void OnUidNextChanged ()
		{
			UidNextChanged?.Invoke (this, EventArgs.Empty);
		}

		/// <summary>
		/// Occurs when the UID validity changes.
		/// </summary>
		/// <remarks>
		/// The <see cref="UidValidityChanged"/> event is emitted whenever the <see cref="UidValidity"/> value changes.
		/// </remarks>
		public event EventHandler<EventArgs> UidValidityChanged;

		/// <summary>
		/// Raise the uid validity changed event.
		/// </summary>
		/// <remarks>
		/// Raises the uid validity changed event.
		/// </remarks>
		protected virtual void OnUidValidityChanged ()
		{
			UidValidityChanged?.Invoke (this, EventArgs.Empty);
		}

		/// <summary>
		/// Occurs when the folder ID changes.
		/// </summary>
		/// <remarks>
		/// The <see cref="IdChanged"/> event is emitted whenever the <see cref="Id"/> value changes.
		/// </remarks>
		public event EventHandler<EventArgs> IdChanged;

		/// <summary>
		/// Raise the ID changed event.
		/// </summary>
		/// <remarks>
		/// Raises the ID changed event.
		/// </remarks>
		protected virtual void OnIdChanged ()
		{
			IdChanged?.Invoke (this, EventArgs.Empty);
		}

		/// <summary>
		/// Occurs when the folder size changes.
		/// </summary>
		/// <remarks>
		/// The <see cref="SizeChanged"/> event is emitted whenever the <see cref="Size"/> value changes.
		/// </remarks>
		public event EventHandler<EventArgs> SizeChanged;

		/// <summary>
		/// Raise the size changed event.
		/// </summary>
		/// <remarks>
		/// Raises the size changed event.
		/// </remarks>
		protected virtual void OnSizeChanged ()
		{
			SizeChanged?.Invoke (this, EventArgs.Empty);
		}

		/// <summary>
		/// Occurs when the message count changes.
		/// </summary>
		/// <remarks>
		/// The <see cref="CountChanged"/> event is emitted whenever the <see cref="Count"/> value changes.
		/// </remarks>
		/// <example>
		/// <code language="c#" source="Examples\ImapIdleExample.cs"/>
		/// </example>
		public event EventHandler<EventArgs> CountChanged;

		/// <summary>
		/// Raise the message count changed event.
		/// </summary>
		/// <remarks>
		/// Raises the message count changed event.
		/// </remarks>
		protected virtual void OnCountChanged ()
		{
			CountChanged?.Invoke (this, EventArgs.Empty);
		}

		/// <summary>
		/// Occurs when the recent message count changes.
		/// </summary>
		/// <remarks>
		/// The <see cref="RecentChanged"/> event is emitted whenever the <see cref="Recent"/> value changes.
		/// </remarks>
		public event EventHandler<EventArgs> RecentChanged;

		/// <summary>
		/// Raise the recent message count changed event.
		/// </summary>
		/// <remarks>
		/// Raises the recent message count changed event.
		/// </remarks>
		protected virtual void OnRecentChanged ()
		{
			RecentChanged?.Invoke (this, EventArgs.Empty);
		}

		/// <summary>
		/// Occurs when the unread message count changes.
		/// </summary>
		/// <remarks>
		/// The <see cref="UnreadChanged"/> event is emitted whenever the <see cref="Unread"/> value changes.
		/// </remarks>
		public event EventHandler<EventArgs> UnreadChanged;

		/// <summary>
		/// Raise the unread message count changed event.
		/// </summary>
		/// <remarks>
		/// Raises the unread message count changed event.
		/// </remarks>
		protected virtual void OnUnreadChanged ()
		{
			UnreadChanged?.Invoke (this, EventArgs.Empty);
		}

		#region IEnumerable<MimeMessage> implementation

		/// <summary>
		/// Get an enumerator for the messages in the folder.
		/// </summary>
		/// <remarks>
		/// Gets an enumerator for the messages in the folder.
		/// </remarks>
		/// <returns>The enumerator.</returns>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		public abstract IEnumerator<MimeMessage> GetEnumerator ();

		/// <summary>
		/// Get an enumerator for the messages in the folder.
		/// </summary>
		/// <remarks>
		/// Gets an enumerator for the messages in the folder.
		/// </remarks>
		/// <returns>The enumerator.</returns>
		/// <exception cref="System.ObjectDisposedException">
		/// The <see cref="IMailStore"/> has been disposed.
		/// </exception>
		/// <exception cref="ServiceNotConnectedException">
		/// The <see cref="IMailStore"/> is not connected.
		/// </exception>
		/// <exception cref="ServiceNotAuthenticatedException">
		/// The <see cref="IMailStore"/> is not authenticated.
		/// </exception>
		/// <exception cref="FolderNotOpenException">
		/// The folder is not currently open.
		/// </exception>
		IEnumerator IEnumerable.GetEnumerator ()
		{
			return GetEnumerator ();
		}

		#endregion

		/// <summary>
		/// Returns a <see cref="System.String"/> that represents the current <see cref="MailKit.MailFolder"/>.
		/// </summary>
		/// <remarks>
		/// Returns a <see cref="System.String"/> that represents the current <see cref="MailKit.MailFolder"/>.
		/// </remarks>
		/// <returns>A <see cref="System.String"/> that represents the current <see cref="MailKit.MailFolder"/>.</returns>
		public override string ToString ()
		{
			return FullName;
		}
	}
}