Unlock the future of email with Stalwart
Step into the future with Stalwart, the open-source powerhouse combining modern email and collaboration features with unmatched security, speed, and scalability.
Stalwart Mail & Collaboration Server
Revolutionize your email infrastructure
All-in-One Platform
Comprehensive support for modern email and collaboration tools, plus robust spam and phishing defenses in an integrated package.
Enhanced Security
Features encryption-at-rest, strong transport security, sender authentication, and proactive security measures.
Highly Flexible
Supports extensive scripting, multi-language search, dynamic configuration rules, and a wide range of storage options.
Built to Scale
Ensures continuous operation with load balancing, partition-resistant fault tolerance, and intelligent system-wide coordination.
All-in-one solution
Integrated email and collaboration for secure and efficient communication.
Unlike any other solution on the market, Stalwart redefines the email server landscape. Traditionally, running a mail and collaboration server meant stitching together multiple outdated components—like MTA, message store, spam filter, calendar, and contacts—each with its own configuration quirks. Stalwart streamlines this into a single, efficient binary with a unified configuration. Built in Rust, a language renowned for memory safety, it delivers a robust, secure foundation for modern communication and collaboration.
JMAP & IMAP
Embrace modern email with JMAP alongside seamless support for legacy protocols.
Collaboration
Complete communication platform with calendars, contacts, and file storage.

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.


Unified collaboration
Everything your team needs to stay connected.
Stalwart extends beyond email with built-in collaboration features that support calendars, contact management, and file sharing—all accessible. Designed for simplicity and performance, these tools ensure smooth coordination and data access across teams and devices.
- Calendar and event scheduling with free/busy support.
- Rich contact management.
- File storage and secure sharing.
- CalDAV, CardDAV and WebDAV support.
- JMAP-based access for modern, real-time syncing.
- Unified platform for communication and collaboration.
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.