Opening SMTP for Postfix

I just installed SuSE 9.0 with Postfix and am trying to test connectivity by telneting to port 25 and get a connection refused. Scanning the box with NMAP shows port 25 closed. If I telnet to localhost on port 25 from the box I connect with the mail system prompt. I tried running the firewall tool in yast2 to allow SMTP but still no luck. Does anyone know where to check to see where I can open this port? Thanks, Eric