cyrus-imapdCyrus IMAP is an email, contacts and calendar server

cyrus-imapd

Cyrus IMAP is a secure, scalable open source server for email, contacts, and calendar services. Designed to run on sealed servers with private mailbox storage, it provides efficient multi-protocol access and enterprise-grade administration capabilities.

Key Features

• Multi-Protocol Support : Access email, contacts, and calendars via JMAP, IMAP, NNTP, POP3, CalDAV, CardDAV, and WebDAV
• High Scalability : Supports multiple concurrent read/write connections to the same mailbox with optimized private database design
• Access Control & Quotas : Per-mailbox access control lists and storage quotas on mailbox hierarchies
• Full-Text Search : Xapian integration for advanced search capabilities across messages and content

Use Cases

• Enterprise Mail Services : Deploy as a self-hosted alternative to commercial mail servers with full administrative control
• Sealed Server Environments : Run on dedicated systems where standard users cannot log in directly
• Unified Communications : Manage email, contacts, and calendars from a single server infrastructure

Who Is It For

Cyrus IMAP is ideal for system administrators and organizations seeking a secure, feature-rich mail server with advanced scalability and control. It suits deployments where privacy, performance, and administrative flexibility are critical requirements.