How can I save an email instead of sending when using SmtpClient?

I am using SmtpClient to send an email with an attachment. However for a certain batch we need to somehow save the MailMessage instead of sending them. We are then thinking/hoping to manually upload the messages to the users drafts folder.

Is it possible to save these messages with the attachment intact (impossible, I would have thought). Or alternatively upload the messages to a folder in the users account?

If anyone has any experience of this, I'd much appreciate a bit of help or a pointer.