Chris,

At risk of using a sledgehammer to kill a fly... have you thought about
doing the following?
1) Do a scan for worldnet addresses.  Copy this list somewhere (into a text
file, etc.)
2) Quiet delete all worldnet addresses.
3) Quiet bulk add all the worldnet addresses but the problem one.

Sure, it ain't elegant, but I think it'd work, no? :)

Regards,
Adam the temporarily sigless