What is Cyrus IMAP?

Cyrus IMAP is an email, contacts and calendar server. Cyrus is free and open source.

  • This is the documentation for version 3.8.3 of Cyrus IMAP: stable branch.

  • The latest development version 3.9.0-alpha0 is at https://www.cyrusimap.org/dev/.


  • 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

Read more in our full list of features.

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.

Need help? We have active mailing lists.

Cyrus IMAP

What is Cyrus SASL?

Simple Authentication and Security Layer (SASL) is a specification that describes how authentication mechanisms can be plugged into an application protocol on the wire. Cyrus SASL is an implementation of SASL that makes it easy for application developers to integrate authentication mechanisms into their application in a generic way.

The latest stable version of Cyrus SASL is 2.1.28.

Cyrus SASL