Delivery Status Notification (DSN) messages are system messages generated by the Transport service that inform the sender of a message about its status. When a message cannot be delivered to a recipient, Exchange will respond to the sender with a message that is associated with a status message. Sometimes, these status messages may not be detailed enough for your liking. In those cases, you can create new messages associated with the DSN code to provide more details to the sender. This is something that has to be done from the Exchange Management Shell.
Working with custom DSN messages
How to do it...
You can use the New-SystemMessage cmdlet to create a custom DSN message:
New-SystemMessage -DSNCode 5.1.1 ` -Text ...