mailcow

mailcow is an open-source Docker-based groupware and email suite built from established components including Postfix, Dovecot, Rspamd, SOGo, Redis, MariaDB, Nginx, and Unbound. Its main advantage is a modern admin UI around a full mail-server stack.

A SaaS product sends on behalf of its customers, so the deciding factors are tenant isolation, whether suppressions can be scoped rather than global, and whether support can answer why one specific account did not receive one specific email. Lifecycle automation and transactional sending usually need to coexist.

Against trial expiry notices, dunning, onboarding sequences, and per-tenant transactional mail, mailcow covers multi-tenant support, event stream, and the suppressions API, and does not cover scheduling and webhook coverage. Whether that gap matters depends on how central those are to the build.

• Multi-tenant: Yes
• Event stream: Yes
• Suppressions API: Yes
• Operating since: Not published
• Scheduling: No
• Best published rate per 1,000: Tiers not published in comparable form
• Deliverability: Self-hosted deliverability depends on DNS, IP history, spam controls, and operator discipline. mailcow bundles Rspamd, DKIM support, quarantine controls, and administration UI around the stack.
• Webhooks: No
• Starts at: Free self-hosted

Self-hosted deliverability depends on DNS, IP history, spam controls, and operator discipline. mailcow bundles Rspamd, DKIM support, quarantine controls, and administration UI around the stack.

Teams that want to self-host a full email and groupware suite.

Small product teams trying to avoid mail-server operations.