Sending email via SMTP that is not current dial-up ISP

I've installed SuSE 8.2 on my laptop and would like to be able to send email via my hometown ISP's SMTP server.I've got an AT&T dialup which I'll be using as my ISP when travelling. This always worked for me before when using a Microsoft OS and Outlook. Currently when I dial into AT&T, there is no problems getting messages from my hometown providers POP server, but if I try to send, nothing happens until I get the message "Error while performing operation: Could not connect to mail.kpunet.net (port 25):Connection timed out." I'm using Ximian 1.2 and kppp as the dialup application. I've tried a variety of SMTP login configurations, (POP before SMTP, Login and Plain) with no sucess. Any suggestions?? Thanks.