IMailFolderGetStreamAsync(UniqueId, String, CancellationToken, ITransferProgress) Method

Task<Stream> GetStreamAsync(
	UniqueId uid,
	string section,
	CancellationToken cancellationToken = default,
	ITransferProgress progress = null
)

public static void SaveAttachments (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);

            // now iterate over all of the attachments and decode/save the content to disk
            foreach (var attachment in item.Attachments) {
                // default to using the sending client's suggested fileName value
                string 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;
                }

                // we'll need the Content-Transfer-Encoding value so that we can decode it...
                ContentEncoding encoding;

                if (string.IsNullOrEmpty (attachment.ContentTransferEncoding) || !MimeUtils.TryParse (attachment.ContentTransferEncoding, out encoding))
                    encoding = ContentEncoding.Default;

                // if all we want is the content (rather than the entire MIME part including the headers), then
                // we want the ".TEXT" section of the part
                using (var stream = client.Inbox.GetStream (item.UniqueId, attachment.PartSpecifier + ".TEXT")) {
                    // wrap the attachment content in a MimeContent object to help us decode it
                    using (var content = new MimeContent (stream, encoding)) {
                        var path = Path.Combine (directory, fileName);

                        // decode the attachment content to the file stream
                        using (var output = File.Create (path))
                            content.DecodeTo (output);
                    }
                }
            }
        }

        client.Disconnect (true);
    }
}