XCON: MTA Crashes Over Slow or Sporadic Network Connection

• Microsoft Exchange Server, version 4.0

SYMPTOMS

When you run Microsoft Exchange Server over a network that is either slow or bursty, the Microsoft Exchange Message Transfer Agent (MTA) might crash with the following error message in the Windows NT Application Event Log.:

   Event ID = 9405:
   An unexpected error has occurred which may cause the MTA to terminate.
   Error:
   Exception e0020002 occurred at Address 77f3cbcd. [BASE TCP/IP DRVR 10]
  (16)

   Event ID = 9405:
   An unexpected error has occurred which may cause the MTA to terminate.
   Error:
   Exception c0000005 occurred at Address 761f62ab.

CAUSE

These problems are due to heap corruption when two or more threads in the MTA try to access the same data structures without proper synchronization. This problem has been particularly noted in networks in which there are a large number of associations being opened and closed between MTA's. Frequently, these MTA failures are associated with slow and unreliable links. For example, an ICMP Ping might return only one out of eight ping attempts.

STATUS

Microsoft has confirmed this to be a problem in Microsoft Exchange Server 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 Product Support Services for more information.

These issues have been fixed in a post SP2 build of the MTA, 994.2. Customers with either 4.0 or SP1 servers will first need to update these to SP2 before applying the patch.

MORE INFORMATION

Before the crash occurs, you might see the following events in the Windows NT Application log:

   A sockets error 10060 on a connect() call was detected. The MTA will
   attempt to recover the sockets connection. Control block index: 12.
   [BASE IL TCP/IP DRVR 54 274] (12)

   Event ID 9215A sockets error 10051 on a connect() call was detected. The
   MTA will attempt to recover the sockets connection. Control block index:
   7. [BASE IL TCP/IP DRVR 10 274] (12)

   Event ID 9224
   A sockets error 10054 on a send() call was detected. The MTA will
   attempt to recover the sockets connection. Control block index: 8. [BASE
   IL TCP/IP DRVR 54 272] (12)