Creating A Postmaster Mailbox In Exchange Server
We’ve all occasionally run into situations in which we have tried to e-mail someone and received an unexpected non delivery report. To a techie, a non delivery report contains a wealth of information that can be used to figure out why the message didn’t reach its intended recipient (I will be discussing this in detail in a future article). For the less technically savvy though, a non delivery report is nothing less than a brick wall in the face. Imagine the frustration that a casual user must feel at receiving a message filled with technical mumbo jumbo, and nowhere to turn to for help.
If you are interested in helping senders who receive a non delivery reports, you can do so by creating a postmaster mailbox. 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.
Before I show you how to get around this issue, I need to explain that the primary reason why Microsoft chose not to include a postmaster mailbox in Exchange 2007 was because the postmaster could potentially receive a lot of spam. Even so, if your company receives e-mail messages from customers, it may be worthwhile to allow senders to reply to NDRs.
Creating A Postmaster Mailbox
The first step in the process is to make sure that no postmaster mailbox currently exists. To do so, open the Exchange Management Shell on your edge transport server. If you don’t have an edge transport server, then use your hub transport server. Now, enter the following command:
Get-TransportServer
When you do, Exchange should show you the e-mail address that is designated as the postmaster address, as shown in Figure A. As you can see in the figure, my test lab does not currently have a postmaster assigned.
Figure A 
You must check to make sure that the postmaster has not already been assigned.
Now, you must enter an e-mail address that can be used by the postmaster account. Although it is possible to use a different e-mail address, Exchange expects you to use [email protected], where yourdomain.com is the name of your domain. There is usually a little less work to be done if you use the e-mail address that Exchange is expecting.
The actual command that you would use to accomplish this requires you to enter the name of your edge transport server. Again, if you don’t have an edge transport server then use the name of your hub transport server. In the command below, you would replace servername with the name of your server, and yourdomain.com with the name of your domain. The command is:
Set-TransportServer servername –ExternalPostmasterAddress [email protected]
Figure B 
You must assign an e-mail address to the postmaster.
Once you enter this command, it’s important to verify that Exchange has been configured to use the postmaster address that you have assigned. To do so, just enter the Get-TransportServer command again. This time, the command should show you the postmaster address, as shown in Figure C
Figure C 
You should see the postmaster address.
As I explained earlier, Exchange Server 2007 sends automated system messages from the postmaster, but there isn’t actually a postmaster mailbox by default. Therefore, it’s up to you to create one. You can create the postmaster mailbox in the same manner as you would create any user mailbox.
Once you have created the postmaster mailbox, you must verify that the e-mail address that was assigned to the mailbox matches the e-mail address that you told Exchange to use for the postmaster. To do so, open the Exchange Management Console, and navigate through the console tree to Recipient Configuration | Mailbox. Now, right click on the Postmaster mailbox and choose the Properties command from the resulting shortcut menu. When you do, you’ll see the postmaster’s properties sheet. You can verify the postmaster’s e-mail address by looking at the E-Mail Address tab, as shown in Figure D.
Figure D 
The E-mail Address tab shows the e-mail address that has been assigned to the mailbox.
Conclusion
In this article, I show you how to create a postmaster mailbox so that senders can reply to the NDRs that they have received. In a future article, I plan on demonstrating how you can use a similar technique to capture and analyze non-delivery reports.