Artie's suggested Rule works a treat and I will now change the action to delete. Now all I have to do is to have my mobile do the same thing...
As long as the account is IMAP ou don't have to change anything on your mobil device. Your non-mobil device will move the offending messages to the trash — assuming it is on and running and Mail is running in either background or foreground.
If we knew what it was we were doing, it wouldn't be called research, would it?
