2 posts tagged with "carddav"

We’re excited to announce the release of Stalwart v0.12, a significant milestone that evolves Stalwart from a powerful mail server into a complete, integrated communication and collaboration platform. This release delivers one of the most anticipated features from our community: native support for calendars, contacts, and file storage—all built directly into the server, with no need for third-party integrations.

Calendars, Contacts & Files – All in One Place​

With v0.12, you no longer need to integrate third-party groupware solutions or run parallel systems to support collaboration. Stalwart now includes first-class support for CalDAV calendars, CardDAV contacts, and WebDAV-based file storage. This means users can manage their events, address books, and documents through any standards-compliant client, seamlessly connected to the same backend that handles their email.

Shared resources such as group calendars, shared address books, and team-accessible file folders are also fully supported, providing a robust foundation for collaboration without the need for external software or services. And, to support flexible collaboration, Stalwart includes full support for the WebDAV Access Control List (ACL) extension, enabling detailed, per-user and per-group permission management.

Improved Spam Filtering​

Another thoughtful addition in this release is the integration of the spam filter with users’ personal address books. Messages from known or trusted contacts are now far less likely to be incorrectly flagged as spam. And if a legitimate message does get misclassified, the system automatically trains the Bayesian classifier to treat future similar messages as legitimate, improving accuracy over time without additional user intervention.

Performance Enhancements​

Under the hood, Stalwart v0.12 introduces several key performance optimizations designed especially for large, multi-node environments. One of the most impactful changes is the introduction of incremental caching: Stalwart now keeps account metadata in memory and only fetches updates when something changes in the database. This significantly reduces load and speeds up response times.

Another major enhancement is the use of zero-copy deserialization. This means Stalwart can read data directly from memory buffers without copying it into new structures, lowering CPU usage and improving throughput. Combined with optimizations that reduce the number of required database queries for common operations, these changes result in a leaner, faster backend that scales much more efficiently.

While these gains may not be noticeable in smaller setups, larger clusters and high-volume deployments will see noticeable performance improvements.

Smarter and Faster Clustering​

We’ve also made big strides in cluster coordination. Previously, Stalwart relied on a UDP-based gossip protocol that performed well but didn’t scale ideally under heavy workloads. With v0.12, cluster behavior is now adaptable based on deployment size.

In small deployments, Stalwart uses Eclipse Zenoh, a lightweight and efficient peer-to-peer pub/sub protocol. For larger infrastructures, you can now choose from robust, scalable backends like Apache Kafka, Redpanda, NATS, or Redis for handling inter-node coordination, state synchronization, and workload distribution.

Looking Ahead: What’s Next?​

With Stalwart v0.12, we're delivering more than just features—we're delivering freedom from fragmented infrastructure. No more patching together third-party services to get the basics of collaboration working. Now, everything—email, calendars, contacts, files, and sharing—lives in a single, efficient, and secure system.

While v0.12 is a major leap forward, we’re already preparing additional enhancements for the next point release. In v0.12.1, you can expect support for CalDAV Scheduling (RFC 6638), enabling automatic meeting invitations and attendee responses. We’re also adding support for event notification alerts via email, so users are always aware of upcoming events, even if they're not logged into their calendars.

Additionally, in the coming months, we will be releasing support for the JMAP for Calendars, JMAP for Contacts, and JMAP for File Storage extensions. JMAP offers a modern, efficient, and JSON-based alternative to legacy protocols, making it faster and easier to develop responsive, real-time collaboration tools. These additions will further streamline the user experience and reduce bandwidth and processing overhead across client-server interactions.

Thank you to everyone who contributed feedback, suggestions, and encouragement. We can’t wait to hear what you build with this release—and we’re just getting started.

We’re happy to announce that Stalwart Labs has been awarded a new grant from the NGI0 Core Fund, established by NLnet with financial support from the European Commission’s Next Generation Internet programme. This funding will support the development of essential collaboration features, marking a major milestone in Stalwart’s evolution from a modern email server into a complete, self-hosted collaboration platform.

This is the second grant Stalwart has received from NLnet, following the initial support we received in March 2023 from the NGI0 Entrust Fund. We are deeply grateful to the NLnet Foundation for their continued trust in our mission to modernize and decentralize communication infrastructure.

Expanding the Vision: From Email to Collaboration​

Stalwart Mail Server was created to address the challenges of self-hosting email by offering a secure, easy-to-maintain, and high-performance solution. With native support for JMAP, IMAP4, POP3, and SMTP, it already serves as a powerful alternative to traditional email solutions, giving individuals and organizations full control over their email systems.

With the help of this new grant, we are now expanding the Stalwart platform beyond email. Development is officially underway on the Stalwart Collaboration Server, a new component that will integrate seamlessly with Stalwart Mail Server. This addition will provide support for calendaring through CalDAV and JMAP for Calendars, contact management using CardDAV and JMAP for Contacts, and file storage and sharing using WebDAV and JMAP for File Management. Together, these features will form the foundation of a fully integrated, open-source collaboration suite.

Our goal is to offer a privacy-focused, vendor-neutral alternative to platforms like Microsoft Exchange. By consolidating email, calendar, contacts, and file sharing into one unified system, Stalwart will give users the ability to self-host their entire collaboration stack without sacrificing modern functionality, scalability, or security.

What the Grant Will Fund​

The new funding will support a series of developments that will be released gradually throughout the year under the AGPL-3.0 license:

• A full-featured CalDAV and CardDAV server will be implemented, allowing users to manage their calendars and contacts directly within Stalwart. This means there will be no need to rely on external software to provide these functions. Users will be able to keep all of their collaboration data in one place, within a single, tightly integrated platform.

• In addition, we will extend Stalwart’s existing JMAP implementation to support JMAP for Calendars and JMAP for Contacts. This will involve developing parsers for JSCalendar and JSContact, as well as creating bidirectional converters between JSCalendar and iCalendar, and JSContact and vCard.

• File storage and management will also become a first-class feature of the platform. A WebDAV-based file storage system will be built on top of Stalwart’s internal blob store. Alongside this, we will implement support for JMAP for File Management, allowing users to upload, organize, and share files using either standard WebDAV clients or JMAP-based applications. The JMAP support will align with the ongoing efforts to standardize file management within the JMAP ecosystem.

• Finally, the grant will fund the implementation of the three most requested features by the Stalwart community. These include support for the IMAP XAPPLEPUSHSERVICE extension, which enables push notifications on iOS devices; automatic DKIM record updates via RFC2136, making it easier to manage DNS records dynamically; and support for exporting Maildir mailboxes with nested folders, improving compatibility and backup workflows.

Acknowledgements​

We would like to express our sincere thanks to the NLnet Foundation and the European Commission for making this work possible. The project is funded through the NGI0 Core 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, as part of grant agreement No. 101092990.

This support plays a vital role in advancing open-source infrastructure and helps ensure that secure, decentralized alternatives remain viable and accessible to everyone.

Looking Ahead​

As we roll out these new features throughout the year, we remain committed to the core values that drive Stalwart’s development: privacy, performance, transparency, and user empowerment. The Stalwart Collaboration Server will transform the platform into a comprehensive, modern collaboration suite — one that is open, scalable, and fully self-hosted.

We look forward to sharing more progress soon. In the meantime, we invite developers, testers, and curious users to follow our work, contribute ideas, and help shape the future of self-hosted collaboration.

Stay tuned, and thank you for your continued support.