XFOR: The Microsoft Mail Connector (PC) MTA Does Not Send NDRs When It Cannot Access an MS Mail Postoffice (277831)

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

When a user on an Exchange Server 5.5 computer sends an e-mail message to a recipient on a Microsoft Mail (MS Mail) server that is connected by means of the Microsoft Mail Connector on the Exchange Server 5.5 computer, the user on the Exchange Server 5.5 computer may not receive a non-delivery report (NDR) if either of following conditions exist:

The MS Mail server is unavailable. -or-
The Microsoft Mail Connector (PC) MTA service cannot access the network shared point of the MS Mail server postoffice.

CAUSE

On the Exchange Server 5.5 computer that is connected to the MS Mail server by the Microsoft Mail Connector, Exchange Server 5.5 increases the number of retries in the delivery process when Exchange Server 5.5 cannot send a message. An NDR is sent to a sender when the number of retries exceeds the limit of Max open retries in the message transfer agent (MTA) properties.

This problem can occur if the MS Mail server is down or the Exchange Server 5.5 computer cannot access the network shared point of the MS Mail server postoffice, because Exchange Server 5.5 cannot start the delivery process and does not increase the number of retry times. Therefore, the number of retries does not exceed the limit of the Max open retries property and an NDR is not sent.

RESOLUTION

A supported fix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Apply it only to computers that are experiencing this specific problem. This fix may receive additional testing. Therefore, if you are not severely affected by this problem, Microsoft recommends that you wait for the next Microsoft Exchange Server version 5.5 service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS

NOTE: In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The typical support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

The English version of this fix should have the following file attributes or later:

Component: Microsoft Mail Connector

   Date          Version      Size        File name         Platform
   -----------------------------------------------------------------
   16-Dec-2000   0.0.0.0000   1,097,728   Q277831engi.exe   Intel

After the fix is installed, the following files will have the listed attributes or later:

   File name      Version
   --------------------------
   Async.exe      5.5.2654.34
   Mt.exe         5.5.2654.34
   X25eicon.exe   5.5.2654.34
   Xtnmsg.dll     5.5.2654.34

MORE INFORMATION

After you install this fix for the Microsoft Mail Connector (PC) MTA service on the servers to replace the fixed files, you need to add the EnforceRetryLimits registry key under the PCMTA_service key on each server for which you want to change the behavior. To do so, you need to edit the registry on each server.

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 add the EnforceRetryLimits registry key:

Start Registry Editor (Regedt32.exe).
Locate the following key in the registry:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\PCMTA_service
To locate the value for the PCMTA_service key:
1. In the Microsoft Exchange Administrator program, click the site_name object, and then click the Configuration object.
2. Click the Connections object, right-click Microsoft Mail Connector, and then click Properties.
3. Click the Connector MTAs tab, and then click MS Mail Connector (PC) MTA Services in the list.
On the Edit menu, click Add Value, and then add the following registry value:
Value Name: EnforceRetryLimits
Data Type: DWORD
Value: 1
Quit Registry Editor.
Restart the Microsoft Mail Connector (PC) MTA service.