Unless third-party programs are designed and tested to run in this configuration, those programs may not work correctly and may adversely affect an Exchange computer. The types of Messaging Application Programming Interface (MAPI) programs that may be affected are custom MAPI store providers, custom gateway and transport providers, and extended MAPI clients. These issues occur because versions of these two products produce a conflict of the MAPI subsystem that may not be cleanly reconciled without breaking either Exchange or Outlook.
For more information about how to create MAPI profiles without installing Outlook, click the following article number to view the article in the Microsoft Knowledge Base:
- Exchange 2000 used with Outlook 2000
- Exchange 2000 used with Outlook 2002
Exchange 2000 used with Outlook 2000 and Outlook 2002 issues and explanationsExchange 2000 installs a copy of the Mapi32.dll file in the Winnt\System32 folder. In Outlook 2000 and later, the MAPI subsystem moves to the Program Files\Common Files\System\Mapi\1033\NT folder. Typically, Outlook installs a "stub" version of MAPI in the Winnt\System32 folder, which routes MAPI calls to the Outlook implementation. If Exchange 2000 is running when Outlook is installed, the Mapi32.dll file is still loaded, and by design is not replaced by the stub DLL; therefore, Exchange 2000 continues to use the MAPI subsystem that is optimized for Exchange 2000.
This configuration might break the installation of custom MAPI providers. Each version of MAPI expects to find the Mapisvc.inf file in a different location. For example, the IMsgServiceAdmin::CreateMsgService method might fail with MAPI_E_NOT_FOUND if the expected Mapisvc.inf file is not updated with the provider information. To avoid breaking the installation of custom MAPI providers, make all the updates to both copies of the Mapisvc.inf file so that both versions of MAPI can see the changes.
For more information about how to make all the updates to both copies of the Mapisvc.inf file, click the following article number to view the article in the Microsoft Knowledge Base:
Article ID: 266418 - Last Review: Mar 29, 2017 - Revision: 2