I'm working with postfix on fedora 9 and I'm attempting to make some changes to a system setup by my predecessor. Currently the postfix server on [mail.ourdomain.com] is setup to forward mail sent to two addresses to another server for processing. The other server [www01.ourdomain.com] receives the email and sends it to a PHP script to be processed. Then that PHP script generates and sends a response to the user who sent the original email.

We're adding more web servers to the system and as a result we've decided to move these processing scripts to our admin [admin.ourdomain.com] server to make them easier to keep track of. I've already setup and tested the processing scripts on [admin.ourdomain.com], and on the mail server doing the forwarding [mail.ourdomain.com] I added [admin.ourdomain.com] to /etc/hosts and also added another, aside from the one for [www01.ourdomain.com], entry to /etc/postfix/transport for [admin.ourdomain.com]. I also restarted postfix as well.

I've tested the communication from [mail.ourdomain.com] to [admin.ourdomain.com] using telnet and the [admin.ourdomain.com] domain and everything runs correctly. But as soon as I change the forward address and attempt to send an email to the mail server I get a bounce message stating "Host or domain name not found. Name service error for name=admin.ourdomain.com type=A: Host not found". If I change the forward settings back to [www01.ourdomain.com] then everything works fine. Is there some setting I'm missing in Postfix? The server itself and telnet work fine it just seems to be postfix that's not able to discover the location of [admin.ourdomain.com].