How to replay Exchange Server 5.5 MTA .dat Files on an Exchange 2000 Server in a mixed mode site

This article describes how to recover messages that are destined for the local store by replaying the messages on a remote Exchange 2000 Server computer, if you have a copy of the original Exchsrvr\Mtdata folder.

In a mixed mode environment, if a backlog occurs for an Exchange Server 5.5 message transfer agent (MTA) because of a hardware failure, an MTA program problem, or any other unexpected event, you may have to replay the Exchange Server 5.5 MTA .dat files on an Exchange 2000 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.

You must have another Exchange Server 5.5 computer in the same site or an Exchange 2000 Server computer to use the following procedure to replay messages.

NOTE: Do not delete any MTA .dat files. If you do so, you will lose messages and you may cause additional damage to the MTA.

To replay messages, perform the following steps:

1. Log on to the Exchange Server 5.5 computer on which the MTA queues are backlogged.
2. Stop the Exchange Server MTA:
   1. Click Start, click Run, and then type cmd.
   2. At the command prompt, type net stop MSexchangeMTA.
3. Start Microsoft Windows Explorer, and then locate the X:\Exchsrvr\Mtadata folder (where X is the local drive on which the folder is located).
4. Make a backup copy of the Exchsrvr\Mtadata folder in another safe location.
5. Delete the Db*.dat files in the Exchsrvr\Mtadata folder on your hard disk.
6. Copy all of the files from the Setup\I386\Bootenv folder on the Exchange Server CD-ROM to the Exchsrvr\Mtadata folder on your hard disk.
7. Remove the read-only attribute from the files that you copied from the CD-ROM to your hard disk. Make sure that none of the files in the Exchsrvr\Mtadata folder on your hard disk have the read-only attribute set.
8. Start the Exchange Server MTA:
   1. Click Start, click Run, and then type cmd.
   2. At the command prompt, type net start MSexchangeMTA.
9. Log on to the destination Exchange 2000 server from which you want to replay the messages.
10. Stop the Exchange 2000 MTA:
    1. Click Start, click Run, and then type cmd.
    2. At the command prompt, type net stop MSexchangeMTA.
11. Start Windows Explorer, locate the X:\Program Files\Exchsrvr folder, and then rename the X:\Program Files\Exchsrvr\Mtadata folder to Mtadata.old.
12. On your Exchange 2000 server, add the Dispatch Remote MTA messages registry value. To do so, you must edit the registry.
    
    To add the Dispatch Remote MTA messages registry value:
    1. Start Registry Editor (Regedt32.exe).
    2. Locate and click the following key in the registry:
       HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeMTA\Parameters\
    3. On the Edit menu, click Add Value, and then add the following registry value:
       Value name: Dispatch Remote MTA messages
       Data type: REG_DWORD
       Radix: Binary
       Value data: 1
    4. Quit Registry Editor.
    NOTE: Remove or disable the Dispatch Remote MTA messages key after you complete remote replay. If you do not remove or disable this key, Exchange Server may send non-delivery reports (NDRs) for all messages after the server returns to its original role.
13. Copy the backup Exchange Server 5.5 X:\Exchsrvr\Mtadata folder to the X:\Program Files\Exchsrvr folder on the Exchange 2000 server.
14. Run the mtacheck.exe /v command against the Exchsrvr\Mtadata folder.
15. Start Performance Monitor, click Add to Chart on the Edit menu, and then add:
    • Object: MSExchangeMTA
    • Counter: Work Queue Length
16. Start the Exchange 2000 MTA:
    1. Click Start, click Run, and then type cmd.
    2. At the command prompt, type net start MSexchangeMTA.
17. In Performance Monitor, watch the work queue length until the queue reaches 0. At that point, all of the remote messages have been replayed.
18. Stop the Exchange MTA:
    1. Click Start, click Run, and then type cmd.
    2. At the command prompt, type net stop MSexchangeMTA. Leave the command prompt window open.
19. Delete the X:\Program Files\Mtadata folder, and then rename the Mtadata.old folder back to Mtadata.
20. In the command prompt window, type cd program files\exchsrvr\bin, and then run the mtacheck /v command.
21. After the queues are scanned, a message is displayed that states, "Database Clean, no errors detected."
22. At the command prompt, type net start MSexchangeMTA to start the Exchange MTA.

After you use these steps, you have replayed your messages.