Cyrus IMAP

Self-Hosted

Open-source IMAP/POP3 server for secure, scalable email management

Overview

Cyrus IMAP is a high-performance open-source mail server implementing IMAP4rev1, POP3, and Sieve filtering. Built for scalability and security, it supports large mailboxes, enterprise deployments, SASL authentication, TLS encryption, LDAP integration, and quota management. It offers shared mailboxes, calendar/contact sync (via CalDAV/CardDAV add-ons), and compliance with email standards. Deployable via package managers, Docker, or source code, it’s ideal for self-hosters and organizations seeking full control over their email infrastructure.

Self-Hosting Resources

Find Official Image on Docker Hub View Source & Docs

Below is a reference structure for docker-compose.yml. ⚠️ Do NOT run blindly. Replace placeholders with official values.

docker-compose.template.yml TEMPLATE


version: '3'
services:
  cyrus_imap:
    image: <OFFICIAL_IMAGE_NAME>:latest
    container_name: cyrus-imap
    ports:
      - "8080:<APP_INTERNAL_PORT>"
    volumes:
      - ./data:/app/data
    restart: unless-stopped

Key Features

Implements IMAP4rev1, POP3, and Sieve email filtering standards
Enterprise-grade security (SASL, TLS, LDAP integration)
Scalable for small to large-scale deployments
Supports shared mailboxes and CalDAV/CardDAV sync (with add-ons)

Frequently Asked Questions

? Is Cyrus IMAP hard to install?

Cyrus IMAP has a moderate learning curve. It can be installed via package managers (apt, yum) or Docker for simplified setup, but configuring advanced features (LDAP, Sieve) requires familiarity with server administration and email protocols.

? Is it a good alternative to Microsoft Exchange Server?

Yes—Cyrus IMAP offers enterprise features like shared mailboxes and security without proprietary costs. It’s ideal for organizations preferring open-source control, though it lacks Exchange’s integrated productivity tools (e.g., built-in chat).

? Is Cyrus IMAP completely free?

Yes—Cyrus IMAP is released under the BSD open-source license, so it’s free to use, modify, and distribute. No licensing fees apply, though server hardware or commercial support costs may exist.

Top Alternatives

Microsoft Exchange Server Search Google

Google Workspace (Gmail for Business) Search Google

IBM Domino Search Google

Tool Info

Pricing Open Source

Category Communication - Email - Mail Delivery Agents

Platform Self-Hosted

Pros

⊕ Full control over email data and infrastructure
⊕ Robust compliance with industry email standards
⊕ No licensing fees (open-source BSD license)
⊕ Highly customizable for specific organizational needs

Cons

⊖ Steeper learning curve for beginners
⊖ Requires manual configuration for advanced features
⊖ Needs additional tools (like SMTP server) for a complete email stack
⊖ Limited graphical interface (mostly command-line driven)