Exchange 2K blocks wrong email address

I have an issue in which a particular address (ie. bob@something.com) has been added to the list of blocked addresses which are automatically sent to the deleted items folder. The problems occurs where Exchange 2K appears to also be blocking another address that has the same beginning section to the naming convention (ie. bob@mydomain.com). Even though the second email address is not on the list, it is also blocked. “bob” seems to be the only common factor. This appears to be a unique problem, and does not occur with any of the other addresses being blocked.

If anyone else has come across this problem I would appreciate any suggestion for a solution.

Thanks,
JR