one NOT listed there, that seems to be commonly suggested...
http://www.argosoft.com/applications/mailserver/
Argosoft Mail server
PS. A SERIOUS WARNING....
Make sure you DO NOT expose a an open mail relay to the internet.
1. It's a gift for spammers
2. That results in you being deep in the brown stuff with your ISP
If it happens, and your ISP is actually on the ball, you will be due a suspension at the very least.
Ideally, as well as security within whichever app you choose, use a firewall as well to allow only your own local clients incoming access
