Applies to: Exchange Server 2007 SP1, Exchange Server 2007
Topic Last Modified: 2009-07-22

This topic provides information about and links to topics that will help you troubleshoot problems that may occur with mail flow in a Microsoft Exchange Server 2007 organization.

Troubleshooting Message Delivery Failures

The Exchange Mail Flow Troubleshooter tool helps provide easy access to various data sources that are required to troubleshoot problems with mail flow, such as non-delivery reports, queue backups, and slow deliveries. The tool will then automatically diagnose the retrieved data, present you with an analysis of the possible root causes, and suggest corrective actions. For more information about the Exchange Mail Flow Troubleshooter tool, see Microsoft Exchange Analyzers.

For more information about how to troubleshoot message failures, see the following topics:

Troubleshooting Certificate and Authentication Issues

Exchange 2007 uses certificates for much of its transport authentication and encryption functionality. Specifically, various implementations of Transport Layer Security (TLS) are used by the Microsoft Exchange Transport service to help secure session communication between transport servers. For more information about how to troubleshoot certificate issues, see the following topics:

Troubleshooting Queue Issues

The routing of a message determines the type of queue in which a message is stored. Exchange 2007 uses the following types of queues: Submission, Mailbox Delivery, Remote Delivery, Poison Message, and Unreachable. For more information about these queues, see Managing Queues.

When you're troubleshooting message delivery issues, the Unreachable queue is often a good starting point. The Unreachable queue is a persistent queue that contains messages that cannot be routed to their destinations. Regardless of destination, all messages that have unreachable recipients reside in this queue. The messages remain in the Unreachable queue until they expire or until the administrator resubmits the messages to the categorizer. For more information about how to troubleshoot messages in the Unreachable queue and other queue issues, see the following topics:

Troubleshooting Non-Delivery Report Issues

Non-delivery reports (NDRs) are a type of delivery status notification. NDRs are generated whenever a message can't be delivered. If a server detects the reason for the delivery failure, it associates the reason to a status code and a corresponding error message is written. For more information about how to troubleshoot NDR issues, see the following topics:

Troubleshooting Readibility Issues

Troubleshooting Transport Agent Issues

Pipeline tracing is a diagnostic feature in Exchange 2007 that enables you to capture diagnostic information about e-mail messages as they encounter transport agents registered on Simple Mail Transfer Protocol (SMTP) events in the transport pipeline. Microsoft Exchange captures verbose information about the changes that each transport agent applies to messages in the transport pipeline in message snapshot files. For more information, see Using Pipeline Tracing to Diagnose Transport Agent Problems.