[Mailman-Users] most secure final config

[wslepecki]

Quick newbie question.  I am finishing installing a mailman server and I
have a security/config question.  What ports do I need to open through
my firewall, which direction, and how do I set up DNS.
 
If im hunch is right, in the firewall, I open smtp out, pop3 in, and the
server will work.  I don't want to open smtp in because I don't want
people to hijack my smtp server.  Then again, does mailman have smtp?  
 
Im tired and lost on this, how do I set this up with the maximum amount
of security.
 
Thanks
Willie