Microsoft introduced a new protocol in Exchange Server 2013 SP1 called MapiHttp (codename Alchemy). This is an Office 365 development to replace the traditional RPC/HTTPS protocol used in Outlook Anywhere.
Outlook Anywhere was developed in the Exchange 2003 timeframe to use Outlook 2003 over the Internet. Outlook is using RPC to communicate with the Exchange server, and the RPC traffic is encapsulated in HTTPS packets. To achieve this an RPC proxy is used. The ‘problem’ here is that this is not too stable, especially not when you have a flaky Internet connection. RPC is never designed to work with network connections like this. Besides this, the RPC proxy is a Windows components and thus a responsibility of the Windows team at Microsoft and not the Exchange team. So if problems arise, the Windows team has to solve this and the only thing the Exchange team can do is wait. Not a desirable solution.