Stalwart Mail Server

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.
• Spam and Phishing filter:
  • Comprehensive set of filtering rules on par with popular solutions.
  • Statistical spam classifier with automatic training capabilities.
  • DNS Blocklists (DNSBLs) checking of IP addresses, domains, and hashes.
  • Collaborative digest-based spam filtering with Pyzor.
  • Phishing protection against homographic URL attacks, sender spoofing and other techniques.
  • Trusted reply tracking to recognize and prioritize genuine e-mail replies.
  • Sender reputation monitoring by IP address, ASN, domain and email address.
  • Greylisting to temporarily defer unknown senders.
  • Spam traps to set up decoy email addresses that catch and analyze spam.
• 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.
  • Security audited (read the report).
• Robust and scalable:
  • FoundationDB or SQLite database backends.
  • S3-compatible blob storage support.
  • Memory safe (thanks to Rust).

Get Started

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.

Support

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.

Funding

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!

License

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 licensing@stalw.art for more details.

Copyright

Copyright (C) 2023, Stalwart Labs Ltd.