How to Disable Outlook/MAPI Access in Exchange Server 2010

MAPI (Microsoft Application programming Interface) or Outlook access can be disabled for all mailboxes on an Exchange Server. Once access is disabled, all client computers running Outlook 2003, Outlook 2007, and Outlook 2010 will receive the following error message:-

Your Microsoft Exchange administrator has blocked the version of Outlook that you are using. Contact your administrator for assistance.

If any user is connected to the Exchange server while you are making registry changes to disable Outlook access, that user will be immediately disconnected and will get the following message:-

Connection to the Microsoft Exchange has been lost. Outlook will restore the connection when possible.

Note:-Registry is very sensitive and critical. Always backup the registry before editing.

How to Configure Registry to Disable MAPI for all mailboxes

1. Open the registry editor.

2. Navigate to the following subkey:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeIS\ParametersSystem

3. On the Edit menu, point to New, and then select String value.

4. Enter the name of this new value Disable MAPI Clients.

5. Double-click on the Disable MAPI Clients value, and in the Edit String box under Value Data, tpe the version number or range as shown below:-

· To disable a specific MAPI client version, type: 12.1234.01

· To disable an open-ended range of MAPI client versions, type: -12.1234.01 or 11.1234.01-

· To disable a range of MAPI client versions, type: 11.1234.01-12.1234.01

· To disable multiple sets of MAPI client versions, use either commas or semicolons to separate the sets as follows: 11.1234.01-11.9999.01;12.1234.01-12.5000.01

How to Determine the MAPI client version for Outlook clients

To view the version of MAPI client, check the version of Emsmbd32.dll file. The version of this file is listed as X.0.Y.Z, but you should enter the value as X.Y.Z. For example, if the version of Exsmbd32.dll file is 12.0.4512.1100, then you should use 12.4512.1100 value to disable MAPI Clients value in the registry.

One registry has been edited with the above values to disable MAPI clients, restart the Exchange Information Store service to apply the changes. And if you do not start the Exchange Information Store service, the service will query the registry at every 15 minutes.