Postmaster In Exchange Server

Symptoms:
By default, the postmaster is used to transmit non delivery reports and any other messages that are generated internally by Exchange. However, Exchange 2007 does not contain a postmaster mailbox. This means that those who receive non delivery reports cannot reply back and ask for help.

Solution:
Get-TransportServer
To check and make sure that the postmaster has not already been assigned

Set-TransportServer servername –ExternalPostmasterAddress postmaster@yourdomain.com
You must assign an e-mail address to the postmaster

Get-TransportServer command again to verify that Exchange has been configured to use the postmaster address that you have assigned

You can create the postmaster mailbox in the same manner as you would create any user mailbox or just assign to existing user using add email address