Stalwart Mail Server is an open-source mail server solution with JMAP, IMAP4, and SMTP support and a wide range of modern features. It is written in Rust and designed to be secure, fast, robust and scalable.

Key features:

• JMAP server:
  • JMAP Core (RFC 8620)
  • JMAP Mail (RFC 8621)
  • JMAP over WebSocket (RFC 8887)
  • JMAP for Sieve Scripts (DRAFT-SIEVE-13)
• IMAP4 server:
  • IMAP4rev2 (RFC 9051) full compliance.
  • IMAP4rev1 (RFC 3501) backwards compatible.
  • ManageSieve (RFC 5804) server.
  • Numerous extensions supported.
• SMTP server:
  • Built-in DMARC, DKIM, SPF and ARC support for message authentication.
  • Strong transport security through DANE, MTA-STS and SMTP TLS reporting.
  • Inbound throttling and filtering with granular configuration rules, sieve scripting and milter integration.
  • Virtual queues with delayed delivery, priority delivery, quotas, routing rules and throttling support.
  • Envelope rewriting and message modification.
• Flexible:
  • LDAP directory and SQL database authentication.
  • Full-text search available in 17 languages.
  • Disk quotas.
  • Sieve scripting language with support for all registered extensions.
  • Email aliases, mailing lists, subaddressing and catch-all addresses support.
  • Integration with OpenTelemetry to enable monitoring, tracing, and performance analysis.
• Secure:
  • Encryption at rest with S/MIME or OpenPGP.
  • OAuth 2.0 authorization code and device authorization flows.
  • Access Control Lists (ACLs).
  • Rate limiting.
• Robust and scalable:
  • FoundationDB or SQLite database backends.
  • S3-compatible blob storage support.
  • Memory safe (thanks to Rust).

Install Stalwart Mail Server on your server by following the instructions for your platform:

• Linux / MacOS
• Windows
• Docker

All documentation is available at stalw.art/docs/get-started.

If you are having problems running Stalwart Mail Server, you found a bug or just have a question, do not hesitate to reach us on Github Discussions, Reddit or Discord. Additionally you may become a sponsor to obtain priority support from Stalwart Labs Ltd.

Part of the development of this project was funded through the NGI0 Entrust Fund, a fund established by NLnet with financial support from the European Commission's Next Generation Internet programme, under the aegis of DG Communications Networks, Content and Technology under grant agreement No 101069594.

If you find the project useful you can help by becoming a sponsor. Thank you!

Licensed under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. See LICENSE for more details.

You can be released from the requirements of the AGPLv3 license by purchasing a commercial license. Please contact [email protected] for more details.

Copyright (C) 2023, Stalwart Labs Ltd.