Topic Last Modified: 2010-02-05

The Microsoft Exchange Server 2010 Management Pack for System Center Operations Manager monitors the Windows Application log on computers running Exchange 2010 and generates this alert when the events specified in the following Details table are logged.

To learn more about this alert, in Operations Manager, do one or more of the following:


Product Name


Product Version

14.0 (Exchange 2010)

Event ID


Event Source

MSExchange Antispam

Alert Type


Rule Path

Microsoft Exchange Server/Exchange 2010/Common Components/Hub Transport and Edge Transport/Agents/Common

Rule Name

Protocol Analysis Background agent warning: The queue used by this agent is full. Open proxy, reverse DNS, and sender blocking are affected.


This Warning event indicates that the work queue that the Protocol Analysis Background agent uses is full. Sender reputation level (SRL) calculations are not affected. As stated in the event description, open proxy, reverse DNS, and sender blocking are affected. Specifically, each connection is processed on a first-in first-out basis. If the queue is full, no new connection data is submitted for processing. Therefore, new connections are delayed until the queue falls below the maximum value. This warning may appear during times when the server is functioning at peak design load.

The maximum queue length is controlled by the msExchSenderReputationMaxWorkQueueSize attribute of the Sender Reputation object in the Message Hygiene options of the Transport Settings in Active Directory. The default value for msExchSenderReputationMaxWorkQueueSize is 1,000.

For more information about sender reputation anti-spam functionality, see:

  • Understanding Sender Reputation

User Action

No user action is required if this event rarely occurs. However, if the warning persists, or this event seems to be causing mail flow interruptions or other problems in your Exchange environment follow one or more of these steps:

  • Review the Application log and System log on your Exchange 2010 servers for related events. For example, events that occur immediately before and after this event may provide more information about the root cause of this error.

  • 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.