Cyrus IMAP

Cyrus IMAP is an open source server for email, contacts, and calendars. It provides email access through IMAP and POP3 while also serving contact and calendar data. It is for people and organizations that need server software covering these three areas. The program combines the listed functions—email, contacts, and calendars—in a single server, with IMAP and POP3 specifically identified as the available email protocols. No specific paid product is identified as a direct replacement, so Cyrus IMAP should not be described as a substitute for any particular commercial server or service based on the available information. One important limitation of the description is that it does not specify the protocols or capabilities provided for contacts and calendars. Only the email protocols, IMAP and POP3, are stated, so users should not assume that the contacts and calendar features match those of a particular paid product.