Blocking Top Level Domains in Exchange 2003

This TechSoup user would like to know how to configure Exchange 2003 to block top level domains such as .ca, .tz, etc. without using a third-party solution. The user is familiar with how to utilizing the sender filtering settings for a particular email address or domain, however, but would like to know how this can be accomplished correctly for a top level domain.

Does you know how to do this and get it to work correctly?

Answer it here!