I have the "Allow non-delivery reports" enabled under Hub Transport> Remote Domains> Message Format.
However, outside users are not receiving NDR messages from our Exchange server letting them know the address is an invalid e-mail address. We do not have Edge Transport . Is there any way to do this without Edge Transport? Everything I have been reading is to use the Edge Transport> Filter Recipient, etc...
I tried looking through the Transport Rules under Hub Transport, but was not successful at finding anything to bounce messages for non-existent users.