This modern protocol for Outlook has been introduced to Exchange Server with Exchange Server 2013 SP1. The protocol removes the dependency to the Windows Server RPC over HTTP component. The reduced complexity enhances the reliability of the client access protocoll. It’s available for quite some time now. 

You can enable MAPI over HTTP on the organization level using the following Exchange cmdlet:?

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Set-OrganizationConfig -MapiHttpEnabled $true

You can still control the protocol setting at the user level by deactivating MAPI of HTTP for certain users, if required:?

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Set-CASMailbox -Identity [USER] -MapiHttpEnabled:$false


If your IT infrastructue is still not ready for MAPI of HTTP, your IT components pretty outdated. It’s time to move forward and to modernize the infrastructure. NOTE
Did you know that MAPI over HTTP connects to Exchange Server using TLS to encrypt the connection? Even though that the protocol name is “overHTTP” it literally uses HTTPS securing the connection.