I got a fair chunk of this implemented today.
Which is interesting, because I haven't really been able to get into hack mode decently for a very long while. Today, I just couldn't stop coding. Hallelujah.
At any rate, the mails I receive now have attachments stripped and saved in the database, and I can detach them with "mm --detach $id". Which is a good start.
I have another really good feeling about this module.