The best way IMHO would be to abstract things a bit, create an interface for UI<->Mail Objects that AOLserver works on (intergrated into OpenACS, use all the fun tools there) and they have message<->Mail Object modules.
You could then have IMAP, POP3, mbox, DB, maildir modules.
I think that would give you a more flexabily webmail intregration and make changes to any part of webmail somewhat pain free.
Of course, this approach would really need to wait until after our first release.
