'Messages with an unreachable destination' queue is frozen

[This topic is intended to address a specific issue called out by the Exchange Server Analyzer Tool. You should apply it only to systems that have had the Exchange Server Analyzer Tool run against them and are experiencing that specific issue. The Exchange Server Analyzer Tool, available as a free download, remotely collects configuration data from each server in the topology and automatically analyzes the data. The resulting report details important configuration issues, potential problems, and nondefault product settings. By following these recommendations, you can achieve better performance, scalability, reliability, and uptime. For more information about the tool or to download the latest versions, see "Microsoft Exchange Analyzers" at http://go.microsoft.com/fwlink/?linkid=34707.]  

Topic Last Modified: 2006-10-06

The Microsoft® Exchange Server Analyzer Tool queries the ExchangeLink Windows® Management Instrumentation (WMI) class to determine the value of the StateFrozen key for the Simple Mail Transfer Protocol (SMTP) Messages with an unreachable destination queue.

If the Exchange Server Analyzer finds that the value of the StateFrozen key for the Messages with an unreachable destination queue on an Exchange server is set to True, the Exchange Server Analyzer displays an error.

A frozen queue means the transport sessions for that queue are stopped. A frozen queue prevents outgoing messages, although new messages can be added.

The Messages with an unreachable destination queue contains messages that cannot reach the intended destination server. For example, Exchange cannot determine a route or a connector to the final destination. Alternatively, all available routes or connectors are marked as down. Messages can accumulate in this queue if any one of the following conditions is true:

  • No route exists for message delivery.

  • An Exchange connector or a remote delivery queue is unavailable.

  • New messages are moved to this queue when an Exchange connector or a remote delivery queue is in a retry status and no alternative available route exists to the connector or the remote destination.

To address this error, manually change the state of the connection by using the shortcut menu on each link queue. When you use the Force Connection command to change a queue state to Active, you immediately enable a connection that sends the messages from that queue. If the error persists, raise the diagnostics logging level of Queuing Engine as described in "For More Information" later in this topic.

For More Information

For more information about how to modify logging settings, see "How to Modify Logging Settings for MSExchangeTransport" in the "Troubleshooting Mail Flow and SMTP" section of the Exchange Server Transport and Routing Guide (http://go.microsoft.com/fwlink/?LinkId=47579).

For more information about how to troubleshoot SMTP queues, see the following Exchange resources: