Over the past few weeks, I've finally been able to setup a mail server to take over my mail from my hosting provider. It wasn't TOO hard to do (thanks to inkroid for helping me debug).
Trustix comes with a few options for mail. I used postfix + courier-imap + mysql + smtp-after-popd + spamassassin + squirrelmail. smtp-after-popd and squirrelmail aren't trustix packages, but they were simple to download from the appropriate website and install.
I used these instructions to get postfix + courier-imap + mysql to talk to each other. Trustix has contrib packages for spamassassin, so, that was a breeze to get running. smtp-after-popd is a little perl daemon which forces people to check their mail before they can send any. A handy feature. Last night i decided to go to mail.alternation.net in my browser, and of course, it went to a trustix/apache default page. I downloaded squirrelmail (which comes with a neat little perl script to configure it) and made apache default to that.