XFOR: Internet Mail Service Does Not Allow Auto Forwarded Messages

When the Microsoft Internet Mail Service is configured to disable auto replies to the Internet, auto forwards to an Internet address are also suppressed.

The Internet Mail Service cannot detect the difference between a message that is an auto reply and a message that is an auto forward. The difference between the messages is that the auto forwarded message has the MAPI property PR_AUTO_FORWARDED set.

To resolve this problem, obtain the latest service pack for Exchange Server version 5.5. For more information, please see the following article in the Microsoft Knowledge Base:
The English version of this fix should have the following file attributes or later:

Microsoft has confirmed this to be a problem in Microsoft Exchange Server version 5.5. This problem was first corrected in Exchange Server 5.5 Service Pack 2.

New code was added to the Internet Mail Service to enable detection of an auto forwarded message. To add the necessary registry key, follow these 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. Start Registry Editor (Regedt32.exe).
2. Locate the following key in the registry:

         HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIMC
         \Parameters
   						

   NOTE: The above registry key is one path; it has been wrapped for readability.
3. On the Edit menu, click Add Value, and then add the following registry value:

         Value Name: AlwaysAllowForwarding
         Data Type:  REG_DWORD
         Value:   1
   						

4. Quit Registry Editor.

After this key is added and the new Internet Mail Service hotfix is applied, auto forwarded messages can be sent while auto replies are disabled.