Can Proofpoint Essentials be used to forward email for non-registered domains?

Proofpoint Essentials only processes email for domains and static IPs registered on our user interface. This is so we can safeguard against the security threat of being used as an open relay.
As such auto-forwarding practices should be relayed using DNS only and cannot be via the Proofpoint Essentials smart host.

 

Also see: 

 

Masquerade domains

554 5.7.1: Relay access denied

Sending to Distribution Groups with external domain recipients