I just completed a HOWTO that will compliment my webtool for a postfix/courier-imap mail server....
http://vipmin.sourceforge.net
The webtool isn't yet available but the guides are complete. I'm putting it through some QA. However, if you're interested in trying it out, send me a PM.
NOTE: This is based on if you choose to use Postfix/Courer-IMAP.. There are alternatives out there....