My first guess would be that it's in /etc/hosts.

well, in /etc/hosts it says name.local for my eth1 interface address (and localhost for 127.0.0.1). to what should i set it instead? i tried to set it to my dyndns hostname, restarted postfix, but still the message in the log says Could not resolve name.local (in reply to MAIL FROM command))
(i guess this is offtopic now)