My organization sends out emails from email@example.com using an Outlook add-in that I developed in 2016. The add-in includes a unique ID in the subject of the email going out so if we get an NDR back, an automated process I wrote can find the details of the specific distribution that was not delivered successfully. The no-reply inbox was set up to reject any emails so I wouldn't get any auto-replies or regular replies or anything, but it was getting NDR's that seem to have been generated by Exchange. For 5 years, every single email in the inbox started with "FW: Delivery delayed:" or "FW: Undeliverable:" followed by the original subject no matter what domain the email had originally been sent to. Recently, network upgraded to a new Exchange server. At first, I was getting nothing in the inbox. I notified network who made a change, and then suddenly I was getting emails, but it included auto-replies and everything. The NDR's I was getting were no longer uniform. Not only does our network team not know how to set up the new server to work this way, they don't seem to know how the old server did either. I'm not sure what version of Exchange we're using or used, but if someone could tell me how to set up any version to work as I've described, that would be extremely helpful.