Dovecot and Squirrelmail
Man, dovecot is more my favorite email imap server software.
I just installed squirrelmail from scratch, and man, its so fast. with my old server, i was using courier and squirrelmail, both debian packages, and man, it'd time out half the time, break others, etc etc etc.
The server isn't any more powerful than the one i had at home, but man, its nice. Except it looks like squirrelmail caches sometimes so some emails don't get moved right away.