Secure and Modern IMAP4rev2 server 🛡️

Stalwart IMAP is an open-source Internet Message Access Protocol server designed to be secure, fast, robust and scalable.

Key features:

• IMAP4 and ManageSieve server:
  • IMAP4rev2 (RFC 9051) full compliance.
  • IMAP4rev1 (RFC 3501) backwards compatible.
  • ManageSieve (RFC 5804) server with support for all extensions.
• Multiple IMAP extensions supported:
  • Access Control Lists (ACL) (RFC 4314)
  • Conditional Store and Quick Resynchronization (RFC 7162)
  • SORT and THREAD (RFC 5256)
  • Message Preview Generation (RFC 8970)
  • And many other extensions...
• JMAP support:
  • JMAP Core (RFC 8620)
  • JMAP Mail (RFC 8621)
  • JMAP over WebSocket (RFC 8887)
  • JMAP for Sieve Scripts (DRAFT-SIEVE-13)
• Flexible and scalable:
  • Pluggable storage backends with RocksDB, FoundationDB, PostgreSQL, mySQL, SQLite, S3-Compatible, Redis and ElasticSearch support.
  • Internal, LDAP 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 and robust:
  • Encryption at rest with S/MIME or OpenPGP.
  • Built-in Spam and Phishing filter.
  • OAuth 2.0 authorization code and device authorization flows.
  • Access Control Lists (ACLs).
  • Rate limiting.
  • Memory safe (thanks to Rust).

Install Stalwart IMAP 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.

Note If you need a more comprehensive solution that includes an SMTP server, you should consider installing the Stalwart Mail Server instead.

If you are having problems running Stalwart IMAP, 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.