Question : How do I identify all machines accessing Exchange 2003 STMP Virtual Server?

I am decommisioning an Exchange 2003 box that is allowing just about anything to connect via SMTP.  I have addressed all the machines listed in the Allowed Relay list, but still have other machines sending internal email because Connection Control is setup as 'All except the list below' rather than 'only the list below'.

My end goal is to identify all the clients\servers that utilize SMTP on this Exchange server.

Suggestions?

Answer : How do I identify all machines accessing Exchange 2003 STMP Virtual Server?

Check message tracking and smtp log.