I have seen a resolution to this question but it does not fix my situation. We are using Exchange on a Small Bus Server 2003 with al lthe latest SP's and updates. We are using a Cisco PIX 501 firewall. DNSSTUFF comes back clean on all reports except the SPF which I have been unsuccesful in correcting.
The IP address the email rejection error is pointing to as being forged is one number off the actaul mail server / MX record IP which is the PIX. I found one article that said the PIX MailSecurity feature was the cause but our PIX has no such feature.
Another intersting item is that several users from inside the same office can email to the email address that is being rejected by another employee in the same network.
Any ideas are appreciated.