The company founded its MS Mail team in 1987, but it was not until it acquired Consumers Software in 1991 to obtain Network Courier that it had a messaging product.
Notable examples include Axigen Mail Server, Kerio Connect, Scalix, Zimbra, HP OpenMail, IBM Lotus Notes, Zarafa/Kopano, and Bynari.
Microsoft used this to interface MS Mail to an email system based on Xenix, for internal use.
[4] In 2014, Exchange 2013 SP1 introduced another variant, this time with a more "normal" HTTP-based stack known as "MAPI over HTTP".
Although the security implications impact all users, inability to represent multiple authorship is generally of little concern in purely hierarchical settings such as traditional businesses and military organizations, primarily impacting legislative and academic institutions.
Several open-source software projects have started working on implementing MAPI libraries, including: