When I setup a mail server from home, I found out that RoadRunner doesn’t block the SMTP or POP3 ports, but does actively scan them looking for and testing for open relays.

Of course, then I found out that most national ISP’s reject SMTP mail from “residential” IP address ranges of other ISP’s. I guess that’s why DynDns.org offers mail forwarding service to their users. One more thing to look up, set up, and maintain. Fun, fun, fun.