If you need an _email_ client, implementing support for the exchange protocol is probably the least of your concerns. Even if the exchange protocol was open, I

If you need an _email_ client, implementing support for the exchange protocol is probably the least of your concerns. Even if the exchange protocol was open, I wouldn't implement support for a specific vendor knowing there are protocols which are more commonly used. Microsoft could instead start by improving their implementation of IMAP in exchange, which is one of the most horrid and buggy implementations of IMAP I've ever seen. This is also true for their IMAP endpoint at office365.com. But it's clear where they stand: outlook is the ultimate corporate lock-in, and it's not due to email by itself.