How to Create Postmaster Mailbox in Exchange Server 2007

By default, system-generated and notification messages sent to external recipients are generated by a user with an e-mail address postmaster@>. By default there is no mailbox-enabled user however in your Exchange organization with that email address. You can choose to give a mailbox-enabled user that default postmaster address manually or you can change the postmaster address by using the Set-TransportServer.  

This command will display the current configuration

[PS] C:\>Get-TransportServer | Fl Name,ExternalPostMasterAddress

Name: DC

ExternalPostmasterAddress :

This command will set the postmaster email address

[PS] C:\>Get-TransportServer | Set-TransportServer -ExternalPostmasterAddress Mail_Info@Pro-Exchange.Be