XCON: MTA Slow to X.400 Links

• Microsoft Exchange Server, version 4.0 and 5.0

SYMPTOMS

The Microsoft Exchange Server message transfer agent (MTA) delivers mail extremely slowly on computers that have multiple X.400 links over TCP/IP if some of the TCP/IP connections are over slow network links.

CAUSE

Flow control within the MTA code above the WINSOCK layer (within the TP0 Transport layer for TCP/IP or Session layer for TP4) for the slowest connection is stalling mail for faster connections.

STATUS

Microsoft has confirmed this to be a problem in Microsoft Exchange version 4.0. A supported fix is now available, but has not been fully regression-tested and should be applied only to systems experiencing this specific problem. Unless you are severely impacted by this specific problem, Microsoft recommends that you wait for the next Service Pack that contains this fix. Contact Microsoft Technical Support for more information.

Microsoft has confirmed this to be a problem in Microsoft Exchange Server version 5.0. This problem has been corrected in the latest U.S. Service Pack for Microsoft Exchange Server version 5.0. For information on obtaining the service pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

   S E R V P A C K

MORE INFORMATION

With the fix applied, the MTA changes the flow control method within the OSI stack above the TCP/IP (or TP4) connection to allow WinSock to handle flow control. This will make the X.400 links faster because WinSock is multithreaded and can handle as much as the MTA can hand to it.

Keywords          : kbbug5.00 kbfix5.00.sp2 XFOR kbusage
Version           : 4.0 5.0
Platform          : WINDOWS
Issue type        : kbbug
Solution Type     : kbfix