Attach MailMessage as Attachment to a Mailmessage

string file = "data.xls";
            // Create a message and set up the recipients.
            MailMessage message = new MailMessage(
               "[email protected]",
               "[email protected]",
               "Quarterly data report.",
               "See the attached spreadsheet.");

            // Create  the file attachment for this e-mail message.
            Attachment data = new Attachment(file, MediaTypeNames.Application.Octet);
            // Add time stamp information for the file.
            ContentDisposition disposition = data.ContentDisposition;
            disposition.CreationDate = System.IO.File.GetCreationTime(file);
            disposition.ModificationDate = System.IO.File.GetLastWriteTime(file);
            disposition.ReadDate = System.IO.File.GetLastAccessTime(file);
            // Add the file attachment to this e-mail message.
            message.Attachments.Add(data);