What is Cyrus IMAP? — Cyrus IMAP 3.2.3 documentation

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# 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 3.2.3 of Cyrus IMAP: stable branch.
- The latest development version 3.3.0 is at https://www.cyrusimap.org/dev/.

## Features

- 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

- Download
  - Get Cyrus
    - Distribution Package
    - Build and Install Yourself
    - External Tools
    - Licensing
  - Release Notes
    - Stable Version
    - Development Version
    - Supported Product Series
    - Development snapshots
    - Older Versions
  - Notes for Packagers
    - Binary naming
    - Sample configuration files
    - Predefined configurations
    - Services in `/etc/services`
- Quickstart Guide
  - Introduction to Cyrus IMAP
    - What is IMAP?
  - Quick install
    - 1. Install Cyrus package(s)
    - 2. Setup the cyrus:mail user and group
    - 3. Setting up authentication with SASL
    - 4. Setup mail delivery from your MTA
    - 5. Protocol ports
    - 6. Configuring Cyrus
    - 7. Launch Cyrus
- Overview
  - Features
    - Security and Authentication
    - Mailbox Management
    - Message Management
    - Calendar and Contact (DAV) Collection Management
    - Storage
    - Load Management
  - Concepts
    - Access Control Lists
    - Login Authentication
    - Quotas
    - New Mail Notification
    - Partitions
    - News
    - POP3 Server
    - The syslog facility
    - Mail Directory Recovery
    - Configuration Directory
    - Message Delivery
    - Sieve, a Mail Filtering Language
    - Cyrus Murder, the IMAP Aggregator
- Setup
  - Compiling
    - Setting up dependencies
    - Compile Cyrus
  - Installing Cyrus
    - Install Cyrus
    - Optional Components
    - Setting up syslog
    - Create Cyrus environment
    - Launch Cyrus
    - Send a test email
    - Checking CardDAV and CardDAV
    - Troubleshooting
  - Upgrading to 3.2
    - 1. Preparation
    - 2. Install new 3.2 Cyrus
    - 3. Shut down existing Cyrus
    - 4. Backup and Copy existing data
    - 5. Copy config files and update
    - 6. Upgrade specific items
    - 7. Start new 3.2 Cyrus and verify
    - 8. Reconstruct databases and cache
    - 9. Do you want any new features?
    - 10. Upgrade complete
    - Special note for Murder configurations
  - Configuration Guide
    - Deployment Scenarios
    - Cyrus Murder: Server aggregation
    - Cyrus Replication
    - Hosted Environments
    - Databases
    - Mailbox Creation Distribution
    - Known Protocol Limitations
    - Authentication and Authorization
    - Performance Recommendations
    - Storage Considerations
    - Supported Platforms and System Requirements
- Operations
  - Man pages
    - (5) Configuration Files
    - (8) System Commands
    - (1) User Commands
  - Administrator Guide
    - Architecture
    - Management
  - Frequently Asked Questions
    - Features
    - Installation Problems
    - Common Feature Requests
    - Common Operational Questions
    - Common Interoperability Problems
- Developers
  - We need your help
  - Contribute docs
    - Overview
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    - Building the files
    - Submitting updates
    - Special Tags
    - Conventions: Man Pages
  - Contribute code and tests
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    - System files and Databases
    - Resources
    - Releasing
  - Cyrus.Works
    - About Cyrus Works
    - How it works
  - Cyrus Internals
    - Cyrus APIs
    - Thoughts & Notes
    - Guidance for Developers
  - Unit Tests
    - Unit Tests
- Support/Community
  - Found a bug?
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  - About
    - What is Cyrus
    - Who Is Cyrus
    - Cyrus Roadmap
    - Cyrus History
    - Cyrus Bylaws

# 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 2.1.27.

Cyrus SASL

- Cyrus SASL