Microsoft does not support installing Microsoft Outlook and Microsoft Exchange Server 2003 (including Exchange System Manager), Microsoft Exchange 2000 Server (including Exchange System Manager), or Microsoft Exchange Server 5.5 on the same computer. The Product Support group does not support the coexistence of Outlook and Exchange on the same computer in a production environment.

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.

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You may want to install Outlook on the same computer with Exchange Server 5.5 or Exchange 2000 to take advantage of certain Outlook components in server-side programs. For most program development needs, Outlook is not necessary on an Exchange 2000 computer. Exchange 2000 and Exchange Server 5.5 include Collaboration Data Objects (CDO), and CDO can provide functionality that is similar to the Outlook Object Model. CDO is designed for server-side use and also avoids the implications that are included in latter versions of Outlook. These implications are described in the following Microsoft Knowledge Base article:

You may also want to create MAPI profiles.

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: You may want to install both Outlook and Exchange on the same computer for demonstration purposes. The following configurations have been tested for demonstration purposes:

•	Exchange 2000 used with Outlook 2000
•	Exchange 2000 used with Outlook 2002

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Exchange 2000 used with Outlook 2000 and Outlook 2002 issues and explanations

Exchange 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: Because the Mapi32 stub library is not in place, setting the stub library registry keys does not affect the computer. All of the programs except Outlook can use the Exchange MAPI implementation. Outlook can load the Msmapi32.dll from the Program files\Common files\System\Mapi\1033\NT folder. For additional information about the Mapi32 stub library, visit the following Microsoft Developers Network (MSDN) Web site:

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