Postfix is one the MTA's I've thought of doing this with. Basically my main
needs are that virtual domains and user accounts are easy to setup and
manage (as it wont be hosting any local domains), able to support mailman
for mailing lists, pop3 & esmtp for secure email access and relaying for my
users. I dont really need imap. Just pop and authenticed smtp will be fine.

Any pointers/help would be gladly appreciated. I'm just trying to make a
free mdaemon like mail service ;p

Kind Regards,
Ian