Downloading ZIP attachments (while skipping any other attachments)

using System;
using S22.Imap;

namespace Test {
    class Program {
        static void Main(string[] args)
        {
            using (ImapClient Client = new ImapClient("imap.gmail.com", 993, "username",
              "password", AuthMethod.Login, true))
            {
                // This returns all messages sent since August 23rd 2012.
                IEnumerable<uint> uids = Client.Search(
                    SearchCondition.SentSince( new DateTime(2012, 8, 23) )
                );

                // The expression will be evaluated for every MIME part
                // of every mail message in the uids collection.
                IEnumerable<MailMessage> messages = Client.GetMessages(uids,
                    (Bodypart part) => {
                        // We're only interested in attachments.
                        if(part.Disposition.Type == ContentDispositionType.Attachment)
                        {
                            // Zip files have a content-type of application/zip.
                            if(part.Type == ContentType.Application &&
                               part.Subtype.toLower() == "zip")
                            {
                                return true;
                            }
                            else
                            {
                                // Skip this attachment, it's not a zip archive.
                                return false;
                            }
                        }

                        // Fetch MIME part and include it in the returned MailMessage instance.
                        return true;
                    }
                );
            }
        }
    }
}