I run Debian stable on all of the servers I work with. It would help both yourself and us if you put Debian in your profile that goes along the left hand side of your posts. The way to do that is to click on the "My LQ" on the bar across the top, then select "Edit Profile" along the left hand side, and the bottom line of that page asks for your distrobution.
Since you are using Debian, I can speak firsthandedly about how good the qmailrocks site does. If you don't like something about qmail, Debian ships out with the exim4 mail server built into it. You could simply reconfigure that to function as a mail server. You can also do things like use Debian's great apt-get utility to install servers, like apt-get install courier-pop or any other server. The command
apt-cache search mail
can show you the mountain of mail applications out there. You could also restrict it a bit more if you know which server type you want, like
apt-cache search qmail
apt-cache search horde
apt-cache search courier
And so forth and so on.