I'm a first timer to the group, though I've been working with Linux for a little while now. I'm trying to set up a mail server, and have chosen Postfix to do it. The mail server sits on a dedicated box inside a DMZ, and I am able to send mail to it both from the internal network and from the web. When I try to relay mail directly from the server, however it fails. I am able to relay mail when I disconnect the server from the DMZ and give it a direct internet connection, however. Most of the places I've checked out only mention having port 25 forwarded on the NAT box to the mail server, and I would think that if I had done that wrong, I wouldn't be getting any mail. Does anyone know of any extra traffic I would have to NAT in order to relay mail?