I’ve found 2 great documents about MS Exchange protocol documentation and MS Exchange and Outlook Standards. The MS Exchange protocol documentation provides detailed technical specifications for the Microsoft protocols that are implemented and used by Microsoft Exchange to interoperate or communicate with other products. It also provides technical specifications for extensions to industry-standard and other published protocols that are used by Microsoft Exchange.
While the MS Exchange and Outlook standards documentation describes how Exchange and Outlook support industry messaging standards and Requests for Comments (RFCs) documents about iCalendar, Internet Message Access Protocol – Version 4 (IMAP4), and Post Office Protocol – Version 3 (POP3).
Hope you find the documentation usefull and until next time.