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

Largest Delivery Queue Length

Instance Name


Sample Interval


Server Role

Ex14. Hub Transport

Warning Threshold


Rule Path

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

Rule Name

Largest Delivery Queue Length - sustained for 5 minutes - Yellow(>200) - Hub Transport.


The Largest Delivery Queue Length performance counter represents the number of e-mail messages that are queued in the largest queue on the specified Exchange Hub Transport server. There can be any number of queues depending on the destination on an Edge Transport server, and these queues may have various numbers of items.

This alert indicates that Largest Delivery Queue Length has exceeded 200 messages for five minutes. When this value is high, the server cannot establish a SMTP session to the other Hub Transport or Edge Transport server. Other symptoms you may experience when this threshold is reached are reduced intra-site, inter-site, and external mail flow. This alert may be caused by one or more of the following conditions:

  • Problem with a specific Hub Transport server or Edge Transport server. For example, one or more required services may not be running.

  • Issues with network connectivity, routers, or firewalls.

User Action

To resolve this alert, do one or more of the following:

  • Run the Mail Flow Troubleshooter. To access the Mail Flow Troubleshooter, click Toolbox in the Exchange Management Console.

  • If the largest delivery queue is to an external domain, use the Nslookup command-line tool to verify that external or remote domain has valid mail exchanger (MX) records. For more information about the Nslookup tool, see Nslookup.

  • Use Telnet to verify that the remote server responds to telnet to port 25. For more information, see Use Telnet to Test SMTP Communication.

  • Resolve your issue by using self-support options, assisted support options, and other resources. You can access these resources from the Exchange Server Solutions Center. From this page, click Self-Support Options in the navigation pane to use self-help options. Self-help options include searching the Microsoft Knowledge Base, posting a question at the Exchange Server forums, and others. Alternatively, in the navigation pane, you can click Assisted Support Options to contact a Microsoft support professional. Because your organization may have a specific procedure for directly contacting Microsoft Technical Support, be sure to review your organization's guidelines first.

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.