XFOR: Exchange SP1 Embedded Messages Appear as Raw MIME

Some messages contain partial MIME headers with UUEncoded bodyparts. In the case of a CONTENT-TYPE header being present (without a full MIME version header), the Microsoft Exchange Server will assume the message to be MIME and will not decode the UUEncoded bodyparts.

This is because the registry fix detailed in the following Microsoft Knowledge Base article applied to partial headers in top-level messages only and not within embedded messages:

Microsoft has confirmed this to be a problem in Microsoft Exchange Server, version 5.0. This problem has been corrected in the latest U.S. Service Pack for Microsoft Exchange Server version 5.0. For information on obtaining the Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

This issue is an extension of the issue detailed in the following Microsoft Knowledge Base article: where UUEncoded bodyparts within a message received via the Microsoft Exchange Internet Mail Service are not decoded into an attachment. Instead, they are left as UUEncoded text within the message.

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.

To correct this problem, apply the fix described above and follow these steps:

1. Start the Windows NT Registry Editor. Use Regedt32.exe if you are running Windows NT 3.51 and either Regedit.exe or Regedt32.exe for Windows NT 4.0.
2. Create the following registry value:
   

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\ 
   ParametersSystem\InternetContent
   
   Value Name: ContentTypeEQMimeVer
   Data Type: REG_DWORD
   Value: 0 or 1 (default is 1)

3. Exit Registry Editor. Stop and restart the Microsoft Exchange Information Store for the change to take effect.

Setting this value to 1 means that if a top-level Content-Type header is found in an inbound Internet Message, the message is treated as a MIME message even if a MIME Version header is missing.

The problem occurs when embedded messages contain MIME headers without the MIME version header being present.