Topic Last Modified: 2010-06-21

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

MSExchange Throttling Service Client

Counter Name

Percentage of Bypassed Submission Requests.

Sample Interval


Server Role

Ex14. Common

Critical Error Threshold


Rule Path

Microsoft Exchange Server/Exchange 2010/Common Components/Transport Throttling Client

Rule Name

High percentage of Transport Throttling Service Client requests are failing - sustained for 30 minutes - Red(>10)


This alert indicates that the server cannot apply throttling policies to client requests for an extended period.

Microsoft Exchange Server 2010 includes a new feature that is known as throttling. This feature is a framework to which other Exchange 2010 Client Access Server (CAS) components can connect to limit user access to the server resources. These components include the following:

  • Outlook Web App (OWA)

  • Exchange ActiveSync (EAS)

  • Exchange Web Services (EWS)

  • IMAP4

  • POP3

  • PowerShell

The throttling framework creates a limits-based system that tracks every user action and drops user requests that exceed specified limits. Additionally, the framework provides a way to slow user requests when the CPU usage for a particular CAS component reaches a certain level.

The performance counters that are used for the MSExchange Throttling Service Client are not used to monitor the Throttling service. Instead, they represent the effectiveness of Transport throttling. The Performance counter object that is logged in the "Percentage of Bypassed Submission Requests" alert represents the percentage of client submission requests that were not handled because the Throttling service was unavailable.

User Action

To troubleshoot this issue, perform the following actions:

  • Verify that the Microsoft Exchange Throttling service (MSExchangeThrottling) is running.

  • Examine running processes or other performance counters to determine whether the server is under a heavy load.

  • Determine whether the configured throttling policies are configured appropriately to reduce overall load on the server.

One or more budget settings in the throttling policies may be set too low to leave sufficient resources available to the server.

To manage throttling policies in Exchange 2010, use the following cmdlets:

  • Get-ThrottlingPolicy

  • New-ThrottlingPolicy

  • Set-ThrottlingPolicy

  • Remove-ThrottlingPolicy

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.

For more information, see Understanding Client Throttling Policies.