I'm a big fan of iRedMail, which is basically a packaged version of Postfix and the other bits that make Postfix cool, like Spamassassin, greylisting and an LDAP or MySQL backend. One thing I wanted with iRedMail is Mailman, my favourite mailing list server. Integrating the two can be a mission though, so here's some instruction to save you from quite a bit of pain.
