The "right" way to do this would be to build an OpenACS front-end to an IMAP server. Vlad Seryakov has built an AOLserver module to interface with an IMAP server, see this thread:
https://openacs.org/bboard/q-and-a-fetch-msg.tcl?msg_id=0003X9&topic_id=11&topic=OpenACS
--cro