MAPI Over HTTP Is the default Outlook Desktop Connection Protocol for Office 365
Microsoft released MAPI over HTTP (the “Alchemy” project) as part of Exchange 2013 SP1 in May 2014. Well before that time, MAPI over HTTP had been running inside Office 365 to shake down the new protocol before it was released to on-premises customers. The replacement for the long-established RPC over HTTP (aka “Outlook Anywhere”) protocol, MAPI over HTTP is designed to accommodate the demands of modern networking environments where devices hop from network to network and seamless mobility is everything.
The natural conclusion for the process has now come to pass. Microsoft is giving Office 365 tenants almost a year’s warning that RPC over HTTP connections will not be supported for Exchange Online after October 31, 2017. Outlook Anywhere is heading for the rubbish heap, but only for Office 365 as on-premises Exchange will continue to support this venerable protocol.