You cannot create mailboxes in Windows Server 2008 SMTP Server. However, you can enter a name and path for an existing mailbox on another server to receive copies of non-delivery reports (NDRs) and undeliverable mail. For example, you can create a mailbox in a client and name it Postmaster. After this option is set, you can review NDRs and undeliverable messages continuously, and correct transmission problems early. Undeliverable messages have a .bad extension.

Reliability and Performance Monitor is an excellent tool for tracking process flow information. Review counter data regularly. Therefore, you can adjust configuration settings before they become problems. You can monitor items such as the number of messages in a queue, the number of connections, the average number of retries and recipients, and the number of bytes sent. Reliability and Performance Monitor is a Windows Server 2008 administrative tool. If values steadily increase for a specific counter, investigate the cause so that you can make adjustments.

For more information about how to use Reliability and Performance Monitor, see Monitoring SMTP Performance and Configuration.

The System, Application, and Security event logs record events for the SMTP service and other computer processes. You can review events in the logs to determine why an error occurred.

Messages may not be delivered because a remote server is down and the queue is filling up, or all messages may be undeliverable for a variety of reasons. If this occurs, you can open the remote transcript (.rtr) files in the Queue directory to determine why messages were not delivered initially, and why they remain queued to be sent again.