Stalwart is a free, open-source mail and collaboration server combining JMAP, IMAP, POP3, SMTP, CalDAV, CardDAV, and WebDAV. Self-hosted and Rust-powered.
Stalwart Mail Server is an open-source, self-hosted mail and collaboration platform that consolidates the protocols a modern email deployment needs into a single Rust-based server. Rather than stitching together separate software for SMTP, IMAP, and calendaring, Stalwart bundles JMAP, IMAP4, POP3, SMTP, ManageSieve, CalDAV, CardDAV, and WebDAV support in one codebase.
The project is maintained by Stalwart Labs, a company founded in 2022 and based in London, United Kingdom. It targets administrators and organizations who want full control over their email infrastructure without depending on legacy tools like Postfix and Dovecot, or on third-party hosted inboxes.
Stalwart supports modern JMAP clients as well as traditional IMAP and POP3 clients, so it works with both contemporary apps and legacy mail software. Built-in DKIM, DMARC, SPF, and ARC support handle message authentication out of the box, with automated DKIM key rotation on a configurable schedule.
Administration is handled through a web-based dashboard covering account, domain, and configuration management, with real-time monitoring and live tracing for troubleshooting. Multi-tenant architecture allows operators to set per-user and per-tenant storage quotas, and integrated DNS management connects directly to providers such as Cloudflare, Route 53, and Google Cloud DNS for automated record management. ACME-based TLS certificate renewal and full Sieve scripting (including every IANA-registered extension) round out the administrative toolset.
Stalwart is free and open source under its Community edition, which includes the core mail server functionality. An Enterprise edition adds premium features, management tooling, and support, licensed per mailbox at roughly 2 euros per mailbox per year for smaller deployments (25 to 499 mailboxes), with the per-mailbox rate decreasing at higher volumes (down to about 0.89 euros per mailbox at 50,000-plus mailboxes). Sponsors contributing at certain monthly tiers on the project's funding page also receive Enterprise licensing and support access.
Yes. The Community edition is free and open source. A paid Enterprise edition exists for organizations that want premium support and additional management features, billed per mailbox.
Stalwart supports JMAP, IMAP4rev2, IMAP4rev1, POP3, SMTP, ManageSieve, CalDAV, CardDAV, and WebDAV in a single server.
Stalwart is designed to be self-hosted. Organizations run it on their own servers or infrastructure rather than subscribing to a hosted inbox service.
Stalwart is written in Rust, which the project cites as contributing to its performance, security, and memory safety.
Stalwart is developed by Stalwart Labs, a company founded in 2022 and based in London, United Kingdom, with an active open-source community on GitHub, Discord, and Matrix.
Yes. Stalwart includes built-in support for DKIM, DMARC, SPF, and ARC, including automated DKIM key rotation.
Stalwart is designed as an all-in-one replacement for the typical Postfix plus Dovecot combination, handling both SMTP delivery and IMAP or JMAP mailbox access in one server.
Yes. Stalwart has a multi-tenant architecture with per-user and per-tenant quotas, making it suitable for hosting mail for multiple organizations or domains.