MTA RTS threads parameter is non-default

[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]  

Topic Last Modified: 2005-11-18

The Microsoft® Exchange Server Analyzer Tool reads the following registry entry to determine its current value:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeMTA\Parameters\RTS threads

If the Exchange Server Analyzer finds the value for RTS threads present and greater than 0 but set to anything other than 1 or 3, a non-default configuration message is displayed.

The RTS threads value is the number of platform threads that handle the Reliable Transfer Service Element (RTSE) level of the Open Systems Interconnection (OSI) stack. RTS threads are responsible for putting data in the queues. You should adjust the RTS threads registry value from the default of 1 to a value of 3 if this message transfer agent (MTA) communicates with multiple Exchange Server version 5.5 computers either within a site or between sites.


This article contains information about editing the registry. Before you edit the registry, make sure you understand how to restore the registry if a problem occurs. For information about how to restore the registry, view the "Restore the Registry" Help topic in Regedit.exe or Regedt32.exe.

To optimize the RTS threads registry value

  1. Open a registry editor, such as Regedit.exe or Regedt32.exe.

  2. Navigate to: HKLM\System\CurrentControlSet\Services\MSExchangeMTA\Parameters

  3. In the right pane, locate and double-click the RTS threads value.

  4. In the Value data field, enter the appropriate value (1 or 3) and click OK.

  5. Exit the registry editor and restart the Microsoft Exchange MTA Stacks service for the change to take effect.

Before you edit the registry, and for information about how to edit the registry, see the Microsoft Knowledge Base article 256986, "Description of the Microsoft Windows Registry" (