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How to lock out certain MAPI clients.

Because of the differences between various versions of MAPI clients -- Outlook 98 versus Outlook 2000, for instance -- it may become necessary to prevent certain versions of MAPI clients from accessing your Exchange Server. For instance, if you want to implement a policy company-wide that everyone not using at least Outlook 2000 will not be allowed to use the MAPI server, you can lock out all versions of Outlook before Outlook 2000.

Lockouts can be implemented against specific versions or ranges of client versions, as well as versions not yet released. This is a good way to discourage people from using beta or untested versions of software with Exchange. Any clients that are blocked and that attempt to connect in this fashion will get the error MAPI_E_LOGON_FAILED.

  1. Start REGEDT32 and navigate to the key HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchange\ISParameters\System.

  2. Add a REG_SZ value named Disable MAPI Clients.

  3. The value for Disable MAPI Clients is a list of values, separated by commas, which describe version numbers or ranges of version numbers that cannot be used with Exchange. Some examples:

    Denies access to Outlook 2000 clients.

    Denies access to all versions of Outlook before Outlook 2000. Note the preceding dash.

    Denies access to all versions of Outlook after Outlook 2000. Note the trailing dash. Use this option with caution as it may cause versions of Outlook that have been patched with Service Packs to work correctly no longer.

    Denies access for all versions between Outlook 2000 and Outlook 2000 SR1.

    You can use more than one of these values in Disable MAPI Clients, as long as you separate them with commas.

  4. Close REGEDT32 and either reboot the server or shut down and restart Exchange. Since Disable MAPI Clients is only read when Exchange starts, this setting will not take effect immediately.

Serdar Yegulalp is the editor of the Windows 2000 Power Users Newsletter.

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