I am having a problem with a large amount of .EXE file attachments being sent in. So I have blocked .EXE extensions and turned off via the global settings in the GUI "Send blocked extension notification to recipient"

The problem is I cant find where you turn off "Send blocked extension notification to SENDER" The .EXE's are coming from spammers and bots with fake addresses and the notifications are queuing up on the server until they time out. Is there any way to turn off this notification?