How to configure SMTP server in Windows Server Step by Step

An SMTP server allows you to send, receive, and forward email messages between users. Learn how to configure SMTP server in ...
Ars Technica

Guide / pointers for setting up an internal-to-public authenticated SMTP relay server with postfix?

Subject does most of the work here, but I'll expand. [edit] Maybe if I had just RTFM'd harder I would've found my answers... I think this will help, but leaving the post up in case anybody else has ...
Ars Technica

My first iptables setup - smtp protocols

4 0 0 ACCEPT tcp -- any any 10.100.100.0/24 anywhere state NEW tcp dpt:ssh 5 1 64 ACCEPT tcp -- any any anywhere anywhere state NEW tcp dpt:smtp 6 730 103K REJECT all -- any any anywhere anywhere ...