XIMS: IMS Routing Incorrectly When Directory Replication Is Enabled

ID: Q223385

The information in this article applies to:
IMPORTANT: This article contains information about editing the registry. Before you edit the registry, make sure you understand how to restore it if a problem occurs. For information about how to do this, view the "Restoring the Registry" Help topic in Regedit.exe or the "Restoring a Registry Key" Help topic in Regedt32.exe.

SYMPTOMS

The Internet Mail Service may route mail incorrectly when directory replication is enabled. Instead of going through a single hop, the mail may go through multiple hops. The issue has to do with the way Exchange Server builds its routing topology when directory replication is enabled.

For example, if a company has three Exchange Server Sites that do not replicate, and the users want to send mail using SMTP, they address mail to each other as user@site1.microsoft.com. Exchange Server looks up site1.microsoft.com in Domain Name System (DNS), and the mail is sent directly. If those three sites begin Exchange Server directory replication in a hub-and-spoke manner, users will gain the benefit of being able to pick users out of the global address list, but all mail from Site1 to Site2 will flow first through the hub by default. This adds an additional hop to the mail flow, and also creates a single point of failure.


CAUSE

When Exchange Server builds its routing table, it doesn't detect that sites are connected by means of Internet Mail Service, and therefore, does not set routing to direct using DNS.


RESOLUTION

A supported fix that corrects this problem is now available from Microsoft, but it has not been fully regression tested and should be applied only to systems experiencing this specific problem. If you are not severely affected by this specific problem, Microsoft recommends that you wait for the next Microsoft Exchange Server version 5.5 service pack that contains this fix.

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 on support costs, please go to the following address on the World Wide Web:

http://www.microsoft.com/support/supportnet/overview/overview.asp
The English version of this fix should have the following file attributes or later:

Component: Internet Mail Service

File name Version
Imcmsg.dll 5.5.2580.0
Msexcimc.exe 5.5.2580.0

This hotfix has been posted to the following Internet location as Psp2imca.zip and Psp2imci.zip:
ftp://ftp.microsoft.com/bussys/exchange/exchange-public/fixes/Eng/Exchg5.5/PostSP2/imc-fix

NOTE: If this product was already installed on your computer when you purchased it from the Original Equipment Manufacturer (OEM) and you need this fix, please call the Pay Per Incident number listed on the above Web site. If you contact Microsoft to obtain this fix, and if it is determined that you only require the fix you requested, no fee will be charged. However, if you request additional technical support, and if your no-charge technical support period has expired, or if you are not eligible for standard no-charge technical support, you may be charged a non-refundable fee.

For more information about eligibility for no-charge technical support, see the following article in the Microsoft Knowledge Base:
Q154871 Determining If You Are Eligible for No-Charge Technical Support
In addition to the new files noted above, the following registry changes must be made to enable this functionality. To make the registry changes, perform the following steps:

WARNING: Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk.

For information about how to edit the registry, view the "Changing Keys and Values" Help topic in Registry Editor (Regedit.exe) or the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe. Note that you should back up the registry before you edit it. If you are running Windows NT, you should also update your Emergency Repair Disk (ERD).
  1. Stop the Exchange Server Internet Mail Service.


  2. Apply the fixed files noted above.


  3. Start Registry Editor (Regedt32.exe).


  4. Go to the following location in the registry:


    5. HKEY_LOCAL_MACHINE\CurrentControlSet\Services\MSExchangeIMC\Parameters
  5. On the Edit menu, click Add Value, and add the following value:


    6. Value Name: OnlySystemMessagesUseCDs
    Data Type: REG_DWORD
    Value: 0x0, 0x1
    Default: 0x0 (not in registry by default)
    After this key is set, Exchange Server will detect that sites are connected by Internet Mail Service, and will set its routing to direct using DNS (1 hop).
  6. Click OK, and quit Registry Editor.


  7. Restart the Microsoft Exchange Internet Mail Service.



STATUS

Microsoft has confirmed this to be a problem in Microsoft Exchange Server version 5.5.

Additional query words: 


Keywords          : 
Version           : winnt:5.5
Platform          : winnt 
Issue type        : kbbug

Last Reviewed: August 2, 1999