Unlock the future of email with Stalwart

Step into the future with Stalwart, the open-source powerhouse blending modern features with unparalleled security, speed, and scalability.


Stalwart Mail Server

Revolutionize your email infrastructure

All-in-One Platform

Comprehensive support for modern email protocols along with robust spam and phishing defenses in an integrated package.

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Enhanced Security

Features encryption-at-rest, strong transport security, sender authentication, and proactive security measures.

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Highly Flexible

Supports extensive scripting, multi-language search, dynamic configuration rules, and a wide range of storage options.

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Built to Scale

Ensures continuous operation with load balancing, partition-resistant fault tolerance, and intelligent system-wide coordination.

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All-in-one solution

Integrated email infrastructure for secure and efficient messaging.

Unlike any other solution on the market, Stalwart redefines the email server landscape. Traditionally, operating a mail server required piecing together multiple components—such as MTA, message store, and spam filter—each developed over 20 years ago with their own configuration formats. Stalwart streamlines this process into a single, efficient binary with a unified configuration. Furthermore, it is crafted in Rust, a language celebrated for its memory safety, ensuring a robust and secure email infrastructure.



Embrace modern email with JMAP, enhancing the way email clients sync with mail servers.

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MTA built for unmatched security, speed, and extensive customization.

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Effectively block unwanted emails and protect against phishing attempts.

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Seamless support for both cutting-edge and legacy email protocols.

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Enhanced Security

Unmatched email security for modern threats.

Stalwart stands at the forefront of secure email technology, providing an unparalleled level of protection for your communications. It employs advanced security measures designed to safeguard data both at rest and in transit, ensuring comprehensive defense against modern threats. With a focus on robust encryption, stringent access controls, and proactive security protocols, Stalwart delivers peace of mind, underlining its commitment to maintaining the highest standards of email security.

  • Encryption at rest with S/MIME or OpenPGP.
  • Strong transport security through DANE, MTA-STS and TLS Reporting.
  • Automatic TLS certificate provisioning with ACME.
  • Granular access control lists, rate limiting and fail2ban.
  • Memory safe.
  • Security audited.

Highly flexible

Next-level email capabilities for dynamic environments.

From sophisticated scripting and dynamic programmability to multilingual search options and versatile storage solutions, Stalwart ensures that your email infrastructure is not only robust and secure but also incredibly adaptable and user-friendly. Whether you're scaling up or drilling down into your data, Stalwart is designed to provide you with a superior email experience.

  • Enhanced Sieve scripting capabilities.
  • Fully programmable with dynamic configuration rules.
  • Powerful full-text search capabilities across 17 languages.
  • Broad array of storage & authentication backends options.
  • Intuitive web-based interface and self-service portal.
  • Hassle-free automatic account configuration and discovery.

Spam & Phishing filter

Robust defense against spam and phishing threats.

Leveraging sophisticated filtering techniques, and real-time threat detection mechanisms, Stalwart ensures your email environment is not only secure but also resilient against evolving email threats. From advanced spam detection to proactive phishing defenses, these tools work in concert to maintain the integrity and reliability of your email exchanges, effectively shielding your organization from both nuisance and malicious threats..

  • Built-in DMARC, DKIM, SPF and ARC support for sender authentication.
  • Comprehensive set of filtering rules on par with popular solutions.
  • Statistical spam classifier with automatic training capabilities.
  • DNS Blocklists checking of IP addresses, domains, and hashes.
  • Collaborative digest-based spam filtering.
  • Phishing protection against homographic, spoofing and other attacks.
  • Trusted reply tracking to recognize and prioritize genuine email 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.

Built to scale

Seamless scalability for millions of mailboxes.

Unlike traditional mail servers, which often rely on coordinators and proxies to scale and are limited by ancient storage formats like Maildir that tie user accounts to a single server, Stalwart is engineered to scale effortlessly from the start. When paired with modern storage backends such as FoundationDB, Stalwart can seamlessly handle millions of mailboxes. This design not only eliminates the need for complex scaling solutions but also ensures robust performance and reliability across extensive email infrastructures.

  • Seamless load balancing and fault tolerance.
  • Node autodiscovery, streamlining network expansion.
  • Network partition-tolerant failure detection.
  • Simplified architecture without coordinators or proxies.