I have a problem with postfix: i cannot send any mail to an external domain.
the message always appears in the mail queue with an MX-Lookup-Error
some information about the system:
The server has 2 NIC's :
eth0 : ip via dhcpcd from router, connects to the internal network
eth1 : ip via dhcpcd from router, the hot wire to the internet
i can reach any known (by me) mailserver via telnet on port 25 as normal user
i can ping every ip/tcp/whateveryouwant as normal user
but no mai delivery to any external mail server.
So what can be the problem?
Has anyone an idea?
This could be caused by lots of things.
Postfix is usually good about logging what's going wrong - look in the /var/log/mail (or whatever file you're logging too) and post what it's saying when you try to send a message.
ok, the postfix is running now for some weeks.
I'd solved the problem by reading and learning the postfix-configuration.
There's also a nice book (in german only) that has helped :
"Das Postfix-Buch" written by Per Heinlein.
It's written in a funny style, spiced up with real-live situations.