Prior to 1994, Carnegie Mellon University (CMU) exclusively used the locally-developed and non-standard Andrew Messaging System (AMS) to service its email communication needs. When, in 1994, CMU wanted to move to a better scalable, standards-compliant mail system that met or exceeded the feature set of AMS, it started the Cyrus project.
Cyrus IMAP is named after Cyrus The Great (559 - 530 B.C.) who founded the Persian kingdom. Cyrus the Great also founded the world's first modern postal system whose motto was: "stopped by neither snow, rain, heat or gloom of night". The Pony Express was based on the Persian system and later the United States Postal Service adopted the slightly modified version of the Persian motto as their own.
At the time of this writing, Cyrus IMAP and Cyrus SASL are amongst the most widely used Free Software products. The largest mail environment reported to run on Cyrus IMAP services over 2.3 million users. A large group of project supporters sustain the continued development of the Cyrus software.