Yep, I was using MAPI as shorthand for both RPC MAPI (which was traditionally used inside corp networks, where port 35 would be open) and RPC-over-HTTP.
There's also a JSON-based web services API that is, as far as I know, unpublished (which OWA and I think the "next gen" Outlook uses).
There's also a JSON-based web services API that is, as far as I know, unpublished (which OWA and I think the "next gen" Outlook uses).