I'm not sure. I use vpopmail, but you probably don't want that unless you're hosting virtual domains. One document that gets cited alot as a good source of information is
'life with qmail'. You can find it at:
I didn't find it all that helpful setting up a complicated 'toaster' type mail abomination, but if you're keeping things simple it might be very useful. Personally I'd like it if everyone in the world said, screw this email stuff, we're going to go with something new based on jabber ( http://www.jabber.org
). Jabber was designed, whereas the email system evolved. When things evolve you get stuff like an animal that breathes and swallows through the same tube. But I'm starting to rant.
Anyway, good luck with it.