hey there,
if you really want to keep with your current path then i can't help you that much, but if your a bit flexable with your approach i can show you how to setup
a mail server that will spam block and virus scan your e-mails and use clamAV to scan your files and all of this with serval easy to use/understand web interfaces
using Postfix (with webmin module) + ClamAV (with wbemin module) + MailScanner (with webmin module) + Dovercot + webmin
http://tlug.dnho.net/?q=node/174