Outlook <-> Exchange Protocols

I'm familiar with what I wrote. :)

Today, we support 5 different data sync protocols (EAS, EWS, REST, MAPI/HTTP, native sync technology), or 6 if you include the deprecated RPC/HTTP protocol.

The first three (likewise for RPC/HTTP) are available for third-parties to consume, which means development on those stacks has to be well thought out as changes have a broad impact across the ecosystem (just like changes in RPC was hard due to RPC being used by everything in the Windows stack).

MAPI/HTTP and the native sync technology are proprietary protocols that are only available to Outlook (and are owned by Exchange/Outlook). There are many features that exist in Outlook desktop, that today, don't exist in the other platforms (e.g., sensitive labeling). By consolidating Mac and mobile clients to a single data sync protocol, we will be able to innovate faster and bring desired features to those platforms. Likewise, we'll continue innovating in Outlook desktop and MAPI (which is a well-established protocol for Outlook desktop, spanning a 20 year history).