There is a "known" issue with that type of setup.
IMF Tune - Unleash the Full Intelligent Message Filter Power
"Andy Izsak" <AndyIzsak@discussions.microsoft.com> wrote in message
> How do I add an IP (of sender SMTP server) to IMF whitelist?
> I have an SMTP server on the lan. Its IP is added in the peremiter and
> on the global accept list. IMF deletes all messages coming from that
> The hot fix, Exchange2003-KB912587-x86.exe is for recipents only.