DOCUMENT:Q152941  29-MAR-1999  [exchange]
TITLE   :XCON: MTA Crashes Over Slow or Sporadic Network Connection
PRODUCT :Microsoft Exchange
PROD/VER:winnt:4.0
OPER/SYS:
KEYWORDS:kbnetwork

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The information in this article applies to:

 - Microsoft Exchange Server, version 4.0 
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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)


Additional query words:

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Keywords          : kbnetwork 
Technology        : kbExchangeSearch kbExchange400 kbZNotKeyword2
Version           : winnt:4.0

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