Topic Last Modified: 2010-02-16

The Microsoft Exchange Server 2010 Management Pack for System Center Operations Manager includes a performance data collection engine that is used to query performance counter objects on computers running Exchange 2010. For this Operations Manager rule, data is collected by using the performance counter specified in the Details table.

To review the value of the performance counter that generated this alert, in Operations Manager, double-click this alert, and then click the General tab. Review the description of the alert that includes the variables specific to your environment.


Product Name


Product Version

14.0 (Exchange 2010)

Object Name

MSExchangeTransport Queues

Counter Name

Retry Non-Smtp Delivery Queue Length

Instance Name


Sample Interval


Server Role

Ex14. Hub Transport

Critical Error Threshold


Rule Path

Microsoft Exchange Server/Exchange 2010/Hub Transport/Transport Queues

Rule Name

Retry Non-Smtp Delivery Queue Length - sustained for 30 minutes - Red(>1) - Hub Transport.


The Retry Non-SMTP Delivery Queue Length performance counter measures the number of messages currently in the retry non-SMTP delivery queue. Messages in this queue are in a retry state because an issue prevented their delivery. If the issue is transient, a subsequent reattempt to send the message may be successful.

This alert indicates that the retry non-SMTP delivery queue length has been greater than 250 for five minutes.This alert may be caused by any of the following:

  • A connector that connects to the non-SMTP mail server might not be functioning correctly.

  • A domain that you connect to via a non-SMTP connector might be down or unreachable.

  • Your DNS server may have some issue resolving fully qualified domain names (FQDNs) to IP addresses.

  • There may be a network connectivity issue that is preventing your server from correctly connecting to destination servers or the Internet. Some possible issues that could affect your connection are:

    • Router or routing issues between your server and the destination.

    • Proxy or gateway server issues.

    • Internet Service providers (ISP) issues such as a cut line, downed system, routing issues, global disturbance, or some other issue.

In Microsoft Exchange Server 2010, non-SMTP delivery is handled by delivery agent connectors and foreign connectors. For information, see the following topics:

  • Understanding Delivery Agents

  • Understanding Foreign Connectors

User Action

To resolve this alert, do the following:

  1. Determine the root cause of the performance issue by doing one or more of the following:

    • Check the destination where the retry messages are being sent to. Verify that your Exchange sever can connect to the destination server, and that the destination is available.

    • Confirm that your DNS server can resolve the FQDNs of the affected domain's mail exchanger (MX) resource records to IP by using the Nslookup command-line tool. For more information about the Nslookup tool, see Nslookup.

  2. Confirm that there are no network connectivity issues preventing your server from correctly connecting to destination servers or the Internet. Use the Ping or PathPing command-line tools to test basic connectivity. Use Ping to isolate network hardware problems and incompatible configurations. Use PathPing to detect packet loss over multiple-hop trips. For more information, see Microsoft Knowledge Base article 325487, How to troubleshoot network connectivity problems.

  3. After you have isolated and corrected the issue, manually submit again any messages that are located in the mailbox delivery queues. To do this, use either Queue Viewer or the Retry-Queue cmdlet and specify the Resubmit parameter. For information about how to retry sending a message, see Retry Queues.

    Note   If you do not want to manually resubmit messages, you can wait for Exchange to do this automatically as specified by the MaxIdleTimeBeforeResubmit parameter.

For More Information

If you are not already doing so, consider running the Exchange tools created to help you analyze and troubleshoot your Exchange environment. These tools can help make sure that your configuration aligns with Microsoft best practices. They can also help you identify and resolve performance issues, improve mail flow, and better manage disaster recovery scenarios. To run these tools, go to the Toolbox node of the Exchange Management Console. To learn more about these tools, see Managing Tools in the Toolbox.