I took on ISA Server 2004 tonight expecting I was going to have my hands full getting it up and running. To my surprise, I had multiple successes mixed with minor failures. The successes was getting it running behind my router/firewall using NAT and enabling both the Firewall and Proxy services. The only failure I have is getting my email to work.

You would think it would be a simple matter of creating a rule allowing POP3 and SMTP through the ISA Server firewall but it's not. At least not in the sense that I'm attempting it.
Maybe not working on it at 2:30 am is the solution. :P Need sleep to get a fresh look. Will report findings later