XADM: MTA Error 9405

• Microsoft Exchange Server, version 4.0

SYMPTOMS

You may see the following error reported by the Microsoft Exchange Server Message Transfer Agent (MTA):

   Event #9405 An unexpected error has occurred which may cause the MTA to
   terminate.
   Error: Exception c0000005 occurred at address 2031561 [BASE
   KERNEL, 27] (16)

CAUSE

One of the causes of this error is a timing error occuring during a connection attempt. The MTA sends a connection request at the transport layer, and may receive a connection confirm for the transport layer before the MTA has prepared the connection at the session layer (CN SPDU).

STATUS

Microsoft has confirmed this to be a problem in Microsoft Exchange Server, version 4.0.

This problem was corrected in the latest Microsoft Exchange 4.0 Server U.S. Service Pack. 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

This timing issue was resolved by readying the session layer connection request (CN SPDU) before sending the connection request for the transport layer.