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MimeKit

IMailFolderExtensionsFetchAsync(IMailFolder, IListUniqueId, MessageSummaryItems, CancellationToken) Method

Asynchronously fetch the message summaries for the specified message UIDs.

Namespace: MailKit
Assembly: MailKit (in MailKit.dll) Version: 4.7.1
Syntax
C#
public static Task<IList<IMessageSummary>> FetchAsync(
	this IMailFolder folder,
	IList<UniqueId> uids,
	MessageSummaryItems items,
	CancellationToken cancellationToken = default
)

Parameters

folder  IMailFolder
The folder.
uids  IListUniqueId
The UIDs.
items  MessageSummaryItems
The message summary items to fetch.
cancellationToken  CancellationToken  (Optional)
The cancellation token.

Return Value

TaskIListIMessageSummary
An enumeration of summaries for the requested messages.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IMailFolder. When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).
Exceptions
ExceptionCondition
ArgumentNullExceptionuids is null.
ArgumentException One or more of the uids is invalid.
ObjectDisposedException The IMailStore has been disposed.
ServiceNotConnectedException The IMailStore is not connected.
ServiceNotAuthenticatedException The IMailStore is not authenticated.
FolderNotOpenException The folder is not currently open.
OperationCanceledException The operation was canceled via the cancellation token.
IOException An I/O error occurred.
ProtocolException The server's response contained unexpected tokens.
CommandException The command failed.
Remarks

Asynchronously fetches the message summaries for the specified message UIDs.

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 IMessageSummary for messages that were requested as well as summaries for messages that were not requested at all.

Example
C#
public static void DownloadBodyAndAttachments (string baseDirectory)
{
    using (var client = new ImapClient ()) {
        client.Connect ("imap.gmail.com", 993, SecureSocketOptions.SslOnConnect);

        client.Authenticate ("username", "password");

        client.Inbox.Open (FolderAccess.ReadOnly);

        // search for messages where the Subject header contains either "MimeKit" or "MailKit"
        var query = SearchQuery.SubjectContains ("MimeKit").Or (SearchQuery.SubjectContains ("MailKit"));
        var uids = client.Inbox.Search (query);

        // fetch summary information for the search results (we will want the UID and the BODYSTRUCTURE
        // of each message so that we can extract the text body and the attachments)
        var items = client.Inbox.Fetch (uids, MessageSummaryItems.UniqueId | MessageSummaryItems.BodyStructure);

        foreach (var item in items) {
            // determine a directory to save stuff in
            var directory = Path.Combine (baseDirectory, item.UniqueId.ToString ());

            // create the directory
            Directory.CreateDirectory (directory);

            // IMessageSummary.TextBody is a convenience property that finds the 'text/plain' body part for us
            var bodyPart = item.TextBody;

            if (bodyPart != null) {
                // download the 'text/plain' body part
                var plain = (TextPart) client.Inbox.GetBodyPart (item.UniqueId, bodyPart);

                // TextPart.Text is a convenience property that decodes the content and converts the result to
                // a string for us
                var text = plain.Text;

                File.WriteAllText (Path.Combine (directory, "body.txt"), text);
            }

            // IMessageSummary.HtmlBody is a convenience property that finds the 'text/html' body part for us
            bodyPart = item.HtmlBody;

            if (bodyPart != null) {
                // download the 'text/html' body part
                var html = (TextPart) client.Inbox.GetBodyPart (item.UniqueId, bodyPart);

                // TextPart.Text is a convenience property that decodes the content and converts the result to
                // a string for us
                var text = html.Text;

                File.WriteAllText (Path.Combine (directory, "body.html"), text);
            }

            // now iterate over all of the attachments and save them to disk
            foreach (var attachment in item.Attachments) {
                // download the attachment just like we did with the body
                var entity = client.Inbox.GetBodyPart (item.UniqueId, attachment);

                // attachments can be either message/rfc822 parts or regular MIME parts
                if (entity is MessagePart) {
                    var rfc822 = (MessagePart) entity;

                    var path = Path.Combine (directory, attachment.PartSpecifier + ".eml");

                    rfc822.Message.WriteTo (path);
                } else {
                    var part = (MimePart) entity;

                    // default to using the sending client's suggested fileName value
                    var fileName = attachment.FileName;

                    if (string.IsNullOrEmpty (fileName)) {
                        // the FileName wasn't defined, so generate one...
                        if (!MimeTypes.TryGetExtension (attachment.ContentType.MimeType, out string extension))
                            extension = ".dat";

                        fileName = Guid.NewGuid ().ToString () + extension;
                    }

                    var path = Path.Combine (directory, fileName);

                    // decode and save the content to a file
                    using (var stream = File.Create (path))
                        part.Content.DecodeTo (stream);
                }
            }
        }

        client.Disconnect (true);
    }
}
See Also