Two KB articles that help interpret Message Tracking Logs:
KB821905
KB246965
A website that Explains what the ID's in the Message Tracking Logs mean:
Swinc
Finally, a script that will report on all the Message Tracking Logs
Outlook Exchange
Day to day happenings of a messaging admin. I'll discuss best practices, problems, and resolutions that I come across as I work with Active Directory, Exchange 2007, Exchange 2003, Office Communications Server, clusters, Archiving Products, and SMTP gateways.