Cyrus IMAP server

The Cyrus IMAP server is electronic mailserver software developed by Carnegie Mellon University. It differs from other Internet Message Access Protocol (IMAP) server implementations in that it is generally intended to be run on sealed servers, where normal users cannot log in.

The mail spool uses a filesystem layout and format similar to the Maildir format used by other popular email servers such as qmail, Courier, Dovecot, etc. Users can access mail through the JMAP, IMAP/IMAP-S, POP3/POP3-S or KPOP protocols.

The Cyrus IMAP server supports server-side mail filtering through the implementation of a mail filtering language called Sieve.

The private mailbox database design gives the server considerable advantages in efficiency, scalability, and administratability. Multiple concurrent read/write connections to the same mailbox are permitted. The server supports access control lists on mailboxes and storage quotas on mailbox hierarchies.

As of version 2.4.17, there is support for CalDAV and CardDAV to provide an integrated calendaring and email solution, and also support for viewing email via an RSS reader.

In terms of user management, it has a simple implementation of SASL which is specified in the Internet Standard RFC 2222.^[2]

Prior to 1994, Carnegie Mellon University's email was based on the locally developed and non-standard Andrew Messaging System (AMS) - written in the early 1980s as part of the Andrew Project. This was very advanced for its day, but had major scalability issues and Carnegie Mellon wanted to move to a standards-compliant mail system that met or exceeded the feature set of AMS.

In 1994 the Computing Services Division at Carnegie Mellon addressed these goals by starting the Cyrus Project. In 1998, Carnegie Mellon placed all of its incoming freshmen (the class of 2002) on the Cyrus server for the first time and in December 2001, board access (which had been mirrored from AMS to Cyrus), was cut over to Cyrus completely. AMS was finally phased out in May 2002.

La División de Servicios Informáticos desarrolló posteriormente el clúster Cyrus "Murder" ^{[ a ]} y, tras varias revisiones, lo implementó en Carnegie Mellon en el verano de 2002.

Varios miembros del equipo de desarrollo de Cyrus en Carnegie Mellon se convirtieron en líderes en el desarrollo de infraestructura de correo electrónico a gran escala en otros lugares: John Gardiner Myers fue arquitecto jefe de la infraestructura de correo de host en America Online ; ^{[ 4 ]} y Rob Siemborski trabajó en la infraestructura de Gmail en Google. ^{[ 5 ]}

En otoño de 2016, Carnegie Mellon anunció la retirada de Cyrus IMAP como su servicio de almacenamiento de correo electrónico, y los usuarios de Cyrus debían elegir entre Microsoft Exchange en el campus y el correo externo de Google "G Suite". ^{[ 6 ]}

Cyrus sigue en desarrollo activo. La Universidad Carnegie Mellon continúa participando activamente en su desarrollo y también proporciona la infraestructura sobre la que se ejecuta cyrusimap.org. ^{[ 7 ]} El personal de Fastmail contribuye con gran parte del trabajo reciente, ya que lo utilizan como parte de su servicio comercial. ^{[ 8 ] [ 7 ] [ 9 ]}

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