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\Concurrent connections to LAN-MTAs

If the Exchange Server Analyzer finds the value for Concurrent connections to LAN-MTAs present and set to anything other than 0x28 (hex) or 40 (decimal), a non-default configuration message is displayed.

The Concurrent connections to LAN-MTAs registry value determines the maximum number of concurrent connections to message transfer agents (MTAs) over the local area network (LAN). MTAs that communicate over a LAN are known as LAN-MTAs. The local MTA may have multiple connections to a remote MTA, depending on its configuration and system load. The maximum number of concurrent LAN-based MTA connections is 240.

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 revert to the default MTA Concurrent connections configuration

  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 Concurrent connections to LAN-MTAs value.

  4. Make sure the Base is set to hexadecimal and in the Value data field, enter 28 and click OK.

  5. Close the registry editor and then 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" (

For more information about the maximum number of concurrent LAN-based MTA connections, see the Knowledge Base article 243402, "XCON: Exchange Server MTA Event ID 9280" (