Update 2014
You can use a built-in action, Modify Exchange properties. For details, have a look at the following tutorial: https://www.adaxes.com/tutorials_AutomatingDailyTasks_AutomateExchangeMailboxConfiguration.htm.
Original
To enable/disable mailbox features, your Business Rule need to update the protocolSettings property of the user.
This is a multi-valued property that should contain the following values to disable mailbox features:
Disable Outlook WebApp: HTTP§0§1§§§§§§, OWA§0
Disable MAPI: MAPI§0§§§§§§§
Disable POP3: POP3§0§§§§§§§§§§
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In the near future, a new Business Rule action for such tasks will be added. It will allow to manage Exchange properties in a more convenient way.