If anyone is interested, my personal notes on how to set up an email server on Ubuntu 9.04 are available.
It uses postfix+courier for Tx/Rx, postfixadmin for domain management, squirrelmail for webmail, spamassassin/clamav for protection, and a few other exciting nibbles.
I’ll do a better writeup when I revamp it for 9.10 when it comes out.