Here is my problem,

I have an ipcop firewall setup and an exchange server behind the firewall. The exchange server itself has its own public ip address as does the firewall. Incoming mail is working fine. Outgoing mail however is presenting a problem. Right now, if someone sends a email, it is getting kicked back on occassion because the mail server that is receiving it is doing a reverse dns on the ipaddress in the header and it is resolving to my firewall box, not the mail server. Is there any way to pass SMTP traffic through the firewall without the firewall tagging its ipaddress on as the source?

Sounds like the firewall is also acting as an SMTP server. Can you verify that?

Firewalls don't change mail headers unless they themselves are setup to forward mail.

The box is not setup as an SMTP Server, but it is setup to forward the SMTP traffic.

That's why it's putting it's headers in each message. It's a relay. No way around that unless you don't relay messages through it. You'd have to shut off the relay part of the firewall and have port 25 open to your Exchange server.