Microsoft does not recommend installing Exchange Server 5.5 and Outlook 2000 or later on the same computer

Microsoft strongly recommends that you avoid installing Outlook 2000 or later and Exchange Server 5.5 (including Exchange Administrator) on the same computer. Unless third party programs are designed and tested to run in this configuration, those programs may not work properly and may impair an Exchange Server. These 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 behaviors occur because these two products ship versions that produce a conflict of the MAPI subsystem that may not be cleanly reconciled without breaking either Exchange Server 5.5 or Outlook.

You may want to install Outlook and Exchange Server on the same computer to take advantage of certain Outlook components in server-side programs. For most program development needs, it is not necessary to install Outlook on an Exchange Server. Exchange 2000 Server and Exchange Server 5.5 include Collaboration Data Objects (CDO), which can provide similar functionality as the Outlook Object Model. However, CDO is designed for server-side use and you may not experience the behaviors that can occur by using later versions of Outlook. For more information about the types of behaviors a customer may experience, click the following article number to view the article in the Microsoft Knowledge Base: You may also want install Outlook and Exchange Server on the same computer to create MAPI profiles, however, it is not necessary to do so to create MAPI profiles. For additional information about how to create MAPI profiles without installing Outlook, click the article number below to view the article in the Microsoft Knowledge Base: You may want to install Outlook and Exchange Server on the same computer for demonstration purposes. The following configurations have been tested for demonstration purposes:

• Exchange Server 5.5 used with Outlook 97
• Exchange Server 5.5 used with Outlook 98
• Exchange Server 5.5 used with Outlook 2000NOTE: Exchange Server 5.5 used with Outlook 2002 has not been tested.

Symptoms and Explanations

Exchange Server installs MAPI subsystems in the Winnt\System32 folder. If the user starts Exchange Server by using 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 the Outlook implementation. If Exchange Server is running Outlook is installed, the Mapi32.dll file is still loaded, and the file is not replaced by the stub DLL. This behavior is by design so that the Exchange Server computer is not impaired.

This configuration can 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 may stop responding with MAPI_E_NOT_FOUND if the expected Mapisvc.inf is not updated with the provider information. To workaround this behavior update both copies of the Mapisvc.inf file so that both versions of MAPI can distinguish the changes.

Because the MAPI32 stub library is not in place, setting the stub library registry keys has no effect on the computer. All of the programs except Outlook can use the Exchange MAPI implementation. Outlook can load the Msmapi32.dll file from the Program files\Common files\System\Mapi\1033\NT folder.

It is possible to install Exchange Server so that the Exchange MAPI providers are not installed. If this procedure is completed, Outlook is able to use the MAPI that it installs in the Program Files\Common Files\System\Mapi\1033\NT folder. However, other MAPI programs may not read files in Mapisvc.inf, and may not be able to load them even if Mapisvc.inf is updated to list them. Reinstalling the Exchange Administrator on the computer corrects this behavior.

If you quit Exchange Server services before you install Outlook, or if you quit Exchange Server and run the Fixmapi.exe file to overwrite the \Winnt\System32 files with the stub library, this procecudure may force Exchange Server to use the Outlook version of MAPI. However, Exchange Server does not support this configuration, and this procedure should not be done in a production environment. The recommended solution is to install these programs on separate computers.

For more information, click the following article number to view the article in the Microsoft Knowledge Base: