How are you connecting to your box to test it with telnet? Are you using an IP on the same network, or even telnet'ing from the same box itself? If you have Postfix to allow relay from my_network (something like that) it will allow relaying from all he IPs on your subnet, so if you're testing it from the local subnetting it will allow relay.

You need to test from an IP.

Postfix is not an open relay by default, so unless you changed a lot of stuff in your main.cf, chances are it's not really an open relay (but check from an outside IP just to make sure).

hi chort sorry for the late reply

yupe i have tried it outside the box using my home internet
and it wasn;t an open relay it replied 554 relay access denied .

so that means it allows relay from inside but not outside (security threat as well from users??)

thanks