Some very interesting ideas in there. I think that it might be best to start off by creating interface for displaying messages, controlling who can use it, controlling how people use it etc.
Maybe at first a POP3/IMAP interface could be placed underneth that interface. Then work out a SMTP->DB interface to handle the messages.
It would be nice to intergrate OpenACS's user authentication with the virtual hosting of various mail servers OR allow the remote mail retrevial.
Okay, well looks like I should really start looking at some code.
