msrpc was used by microsoft to seamlessly create a client/server model in windows nt, with very little effort. for example, the windows server domains protocols are entirely msrpc based, as is microsoft's dns administrative tool. microsoft exchange server 5.5's administrative front-ends are all msrpc client/server applications, and its mapi was made more secure by "proxying" mapi over a set of simple msrpc functions that enable encryption at the msrpc layer without involving the mapi protocol.