Originally Posted by roberto8080
OK checking out the logs I see that I was an open-relay
Temporarily I just limited the SMTP to the local machine. Anyway, is there any guide of tuning and securing Postfix in ISPConfig once installed?
The best way is to limit SMTP relaying to the IP 127.0.0.1 and the enable SMTP-Auth for your mailusers.
Have you read one of the howtos? In each howto is a section on how to configure postfix for smtp-auth. You will find the howtos on the ISPConfig documentation page or at www.howtoforge.com