Stalwart Mail Server

Stalwart Mail Server implements a full suite of email and collaboration protocols, including JMAP, IMAP4, POP3, SMTP, CalDAV, CardDAV, and WebDAV. It provides standard mail services such as message storage, retrieval, and delivery, while also offering extensions for Sieve scripting, quota management, blob handling, and WebSocket support. The SMTP component includes built‑in DMARC, DKIM, SPF, ARC, DANE, MTA‑STS, and TLS reporting, along with automated key rotation, inbound throttling, and flexible routing rules.

The server extends beyond email to unified calendaring, contact management, and file storage through JMAP and the respective DAV protocols. Fine‑grained sharing and access controls are supported, and the system can be configured with scripting, multi‑language search, and various storage back‑ends. Its design emphasizes security, speed, and robustness, leveraging Rust’s memory‑safety guarantees.

Stalwart is released under the AGPL‑3.0 license, is self‑hostable, and offers a free tier without subscription requirements. It targets organizations that need a single, open‑source solution for secure, scalable mail and collaboration services, and it aims to replace the traditional stack of separate components with a unified binary and configuration.