One of the highlights of Defrag was the email BoF dinner on Sunday night, where I finally got to meet Scott Chasin. Founder of MX Logic, he's got an incredible depth of knowledge on the mail world. One of the things he told me about there was a network device by Blue Coat, that actually understands MAPI RPC communication between Outlook and Exchange, and uses that knowledge to reduce the bandwidth used within corporate WANs. In dispersed companies, mail servers may end up centralized at HQ for regulatory or administration reasons, so remote branch offices can put a severe load on the network. Their MAPI proxy can dramatically reduce the strain by breaking the calls down into their components, and compressing each one.
That's nice Pete, but why are you so interested? It's a practical demonstration that it's possible for a third party to sit between Outlook and Exchange and understand their network traffic. That means you can use a reverse-engineered MAPI RPC implementation as a reliable API to Exchange's data store, a key route to breaking open that silo. It doesn't help me implement that at all, but it does show it's worth trying.
Pete Warden's blog 