Mailcow

Mailcow is a fully open-source, Docker-based mail server suite that provides a complete email hosting solution. It bundles Postfix (MTA), Dovecot (IMAP/POP3), Rspamd (spam filtering), SOGo (groupware/webmail), ClamAV (antivirus), and several other components into a cohesive, easy-to-deploy package.

The web-based admin interface (mailcow UI) provides comprehensive management of domains, mailboxes, aliases, rate limiting, spam filter settings, and DKIM/DMARC configuration. Administrators can manage multiple domains and delegate domain-level administration to customers. The interface is clean, modern, and responsive.

Mailcow's Docker architecture means the entire mail stack runs in isolated containers with a single docker-compose file. Updates are handled through a simple update script that pulls new container images. This containerized approach dramatically simplifies deployment and maintenance compared to traditional bare-metal mail server setups.

Spam filtering through Rspamd is excellent, using a combination of rules, Bayesian learning, DNS blocklists, DKIM verification, and neural network analysis. The integration with ClamAV provides virus scanning for incoming and outgoing email.

SOGo provides a full groupware experience with webmail, calendar, contacts, and ActiveSync support for mobile devices. For hosting providers who want to offer self-hosted email as a service, Mailcow provides a production-ready platform with minimal configuration required.