You can monitor transmissions and make configuration adjustments to prevent problems. If errors still occur, there are several places to begin troubleshooting.
You can set up your system to regularly review transmissions and resolve bottlenecks before they cause problems.
Set up a mailbox to receive NDRs and undeliverable mail
You cannot create mailboxes in Microsoft® SMTP Service. 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. Once this option is set, you can review NDRs and undeliverable messages continuously, and correct transmission problems early. Undeliverable messages have a .bad extension.
Use performance counters to gauge server load and identify bottlenecks
Performance Monitor is an excellent tool for tracking process flow information. Review counter data regularly so 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. Performance Monitor is a Windows NT® Server administrative tool. If values steadily rise for a specific counter, investigate the cause so you can make adjustments.
For more information about using Performance Monitor, see Monitoring SMTP Performance and Configuration.
After an error has occurred, use the following methods to begin troubleshooting the problem.
The System, Application, and Security event logs record events for Microsoft SMTP Service and other computer processes. You can review events in the logs to determine why an error occurred.
For more information about using Event Viewer, see Monitoring System Processes.
Review .rtr and .ltr files in the Queue directory to determine why messages aren't being delivered
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 transcripts in the Queue directory to determine why messages were not delivered initially and why they remain queued to be sent again. There are two types of transcripts: .rtr (remote transcript) and .ltr (local transcript).