Setting the Postmaster address in Exchange

Somebody asked me today, whether it is a good idea to set the postmaster address in Exchange. Well, short answer: yes! It's is even mandatory according to RFC 5321 section 4.5.1.

For Exchange 2010 you will have to use the Set-TransportConfig cmdlet:

Set-TransportConfig -ExternalPostmasterAddress <ExternalPostmasterSMTPAddress>

For Exchange 2007 you will have to use the Set-TransportServer cmdlet for each Hub and Edge transport server:

Set-TransportServer <TransportServerName> -ExternalPostmasterAddress <ExternalPostmasterSMTPAddress>

For both Exchange 2007 and 2010, you will have to create a mailbox (or other object) with the corresponding SMTP address.In Exchange 2003 the account which had created the Exchange Organization automatically receives the postmaster SMTP proxy address. Be sure to check whether that account (or SMTP address) is still present. 

Further Reading

RFC 5321

Managing the External Postmaster Address (Exchange 2007)

Configure the External Postmaster Address (Exchange 2010) 

Exchange Server 2003 Scheduled Maintenance Tasks