e-mail issues- canīt send mails to any domain but mine

[pewichali]

Hi, I installed ISPConfig with the perfect setup OpenSuse 10.2 all seems to work fine the domain, the site, i have no problems login and managing accounts; but i have an issue with the email. It happens that i can receive mails to mydomain.net from any domains but when im sending mails it only delivers mail to mydomain.net i cant send mails to any other domain different to mine. What can it be, plz helpme that's the only failure im experiencing with it.

Checking the log on /var/log/mail it says something like:
to=<dude@mydomain.net>, relay=none, delay=0.24, delays=0.07/0.01/0.17/0, dsn=5.4.6, status=bounced (mail for www.mydomain.net loops back to myself)
is it something i did wrong???