MTA event ID 57 on bridgehead servers (300048)

IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows Registry

SYMPTOMS

You may see slow mail flow on message transfer agent (MTA) or connector bridgehead servers. In addition, you may see the following event logged in the Application event log:

Source: MSExchangeMTA
Category: X.400 Service
Event:57
User: N/A
Description:
The limit on the number of associations allowed to and from entity /O=ORGANIZATION/OU=SITENAME/CN=CONFIGURATION/CN=SERVERS/CN=SERVERNAME/CN=MICROSOFT MTA has been reached. The limit is 9. [MTA MAIN BASE 1 43] (14)

RESOLUTION

WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

To improve the performance on the bridgehead servers, change the entries in this registry key to a value of 6.

Note You can use a value of 6 for single processor servers. And, you can use a value of 8 for multiprocessor servers.

For more information, click the following article numbers to view the articles in the Microsoft Knowledge Base:

265186 MTA fanout slows on multiprocessor servers and messages back up in information store

327260 MTA slows down or stalls in Exchange Server 5.5 and messages back up in the private information store

To do this, follow these steps:

Start Registry Editor (Regedt32.exe).
Locate the Dispatcher threads, Kernel threads, RTS threads, and Transfer threads values under the following key in the registry:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeMTA\Parameters
NOTE: The above registry key is one path; it has been wrapped for readability.
On the Edit menu, click DWORD, type 6 for single processor servers or type 8 for multiprocessor servers, and then click OK.
Quit Registry Editor.

MORE INFORMATION

The default value for Dispatcher threads and RTS threads is 2. The default value for Kernel threads and Transfer threads is 3.

For more information, click the following article number to view the article in the Microsoft Knowledge Base:

234280 How to increase the ability of the MTA to pass mail over slow network connections