We have a access rule that does not allow larger than 4000 kB message size for some of our users. The email is rejected at Gwia which is correct and sent back to the Sender as a undeliverable but that undeliverable message is not sent to Postmaster we have setup on our Gwia gateway.

I thought that all undeliverables will be sent to the Postmaster if one is setup. Am I missing something in our setup?