Cyrus IMAP – email, contacts and calendar server

Cyrus IMAP is an email, contacts and calendar server.

The Cyrus IMAP server differs from other IMAP server implementations in that it is generally intended to be run on “sealed” servers, where normal users are not permitted to log in. The mailbox database is stored in parts of the filesystem that are private to the Cyrus IMAP system. All user access to mail is through the IMAP, NNTP, or POP3 protocols.

The private mailbox database design gives the server large advantages in efficiency, scalability, and administrability. 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.

Cyrus has been under active development since the year 1993 when the project was launched at Carnegie Mellon University. It’s used in production systems around the world, at universities and in private enterprise.

Features include:

  • Speed.
  • Security.
  • Efficiency.
  • Search.
  • CardDAV and CalDAV support.
  • Robust data storage.
  • Replication.
  • Scalable for large installations.
  • Flexible filtering support through Sieve.
  • Supports antivirus and antispam toolkits.
  • Handles deliverability: SPF, DKIM, DMARC.
  • Extensive authentication options, through Cyrus SASL.
  • JMAP support.
  • Long list of supported standards.

Website: www.cyrusimap.org
Support: GitHub Code Repository
Developer: Carnegie Mellon University
License: BSD

Cyrus IMAP is written in C. Learn C with our recommended free books and free tutorials.

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