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.

We are happy to announce that third-party OpenID Connect (OIDC) authentication support has now been open-sourced under the AGPL-3.0 license in Stalwart Mail Server version 0.11.5. This means that users can now configure Stalwart Mail Server to authenticate against external OIDC providers, such as Keycloak, without requiring an Enterprise subscription.

Stalwart Mail Server has supported OIDC authentication for several months, allowing it to function as either an OIDC provider or an OIDC client authenticating against an external provider. Until now, only the ability to act as an OIDC provider was included in the Open Source edition, while authentication via external OIDC providers was reserved for Enterprise users. By making this functionality freely available, we are reinforcing our commitment to openness and ensuring that more users can take advantage of modern, federated authentication without barriers.

With this change, organizations that rely on external OIDC identity providers can seamlessly integrate Stalwart Mail Server into their existing authentication workflows at no cost. Whether you are using Keycloak, Auth0, or another OIDC-compliant solution, Stalwart Mail Server now offers complete flexibility in how you manage authentication.

Why is Stalwart Not 100% Free?​

At Stalwart Labs, our goal is to provide a robust and feature-rich mail server solution. However, sustaining long-term development for a project of this scale requires significant financial resources. At present, open-source sponsorships alone do not generate sufficient funding to cover these costs entirely.

To ensure that Stalwart Mail Server continues to evolve and improve, we offer a paid Enterprise version. Revenue from Enterprise subscriptions allows our team to dedicate full-time efforts to development, ensuring the continuous enhancement of both the open-source and paid versions. This funding model allows us to introduce new features while maintaining the high standards that make Stalwart Mail Server a leading solution in the industry.

Furthermore, the existence of an Enterprise edition directly benefits the open-source community. By sustaining active development, we can periodically release new features into the open-source version, as we have done with third-party OIDC support. It is worth noting that even the community edition of Stalwart Mail Server already provides more features than any other open-source or commercial mail server available today. We are dedicated to maintaining and expanding this competitive edge.

If you would like to support open-source development and help accelerate the release of additional features as open-source, we invite you to become a sponsor. Your sponsorship plays a vital role in the project's sustainability and future growth. Thank you for your support and understanding.

Join Us at FOSDEM 2025​

To learn more about Stalwart Mail Server and its latest developments, we invite you to watch our talk at FOSDEM 2025. The session will take place tomorrow, Saturday, February 1st, at 12:00 PM Central European Time in Brussels. If you cannot attend in person, you can follow the presentation online at fosdem.org.

We look forward to sharing more about the project and engaging with the community at this exciting event!

As we step into 2025, we're excited to share some significant enhancements to Stalwart Mail Server version 0.11.0, starting with a complete overhaul of its built-in spam filter. These changes bring dramatic improvements in speed, ease of use, and flexibility while addressing feedback from our community. Here’s a closer look at what’s new.

A Faster, Smarter Spam Filter​

In earlier versions of Stalwart Mail Server, the spam filter was implemented as a Sieve script. This design choice was inspired by platforms like Rspamd, which use scripting languages like Lua to allow customizations. However, over time, we identified two key challenges with this approach. First, because it was an interpreted script, the spam filter’s performance was slightly slower than we’d like. Second, many users found it complicated to update the script when adding custom rules or configuring custom DNSBL (Domain Name System Blocklist) servers.

To address these issues, we rewrote the spam filter entirely in Rust. The result is a system that is five times faster than before, delivering superior performance while keeping resource usage minimal. Moreover, defining new rules or adding DNSBL servers is now as simple as editing the configuration file—no scripting expertise required. This shift eliminates complexity while maintaining the high level of customization our users expect. For those who still need advanced control, Stalwart continues to support custom Sieve scripts and expressions, ensuring maximum flexibility.

Enhanced Training​

One of the most requested features we’ve added is the ability for end users to train their own spam filter Bayesian model. Now, users can customize their spam filtering by simply moving messages to and from the "Junk Mail" folder or by adding and removing the $Junk flag. This personalized approach allows each account to maintain its own tailored spam filter, providing greater accuracy and user satisfaction.

Improved Performance​

This update isn’t just about the spam filter. We’ve also made broader performance enhancements to Stalwart Mail Server. Previously, we relied on LRU (Least Recently Used) caches. With this release, we’ve switched to scan-resistant S3-FIFO caches, offering better performance under heavy workloads. Additionally, we’ve optimized Stalwart’s handling of large distributed SMTP queues, ensuring smoother operation in clustered environments. These changes make Stalwart even more capable of handling demanding enterprise setups.

Meet Us at FOSDEM'25​

We’re thrilled to announce that Stalwart Mail Server will be featured at FOSDEM’25! Join us on February 1st at 12:00 PM in Brussels, where we’ll showcase these new features and share insights into what’s coming next for Stalwart. This is a fantastic opportunity to connect with our team, ask questions, and explore how Stalwart can power your email infrastructure.

Upgrade Today​

These improvements are available now, and we’re confident they’ll make a big difference for administrators and users alike. Whether you’re drawn to the speed of the new spam filter, the enhanced training capabilities, or the overall performance boosts, this update is designed to help you get the most out of Stalwart Mail Server.

As always, thank you for choosing Stalwart. We’re committed to delivering a reliable, feature-rich email server that evolves with your needs. Here’s to a productive and spam-free 2025!

Today we are announcing the release of Stalwart Mail Server version 0.10.7, an update that brings two of the most requested features from our users: robust troubleshooting tools and support for external recipients on mailing lists. This update also introduces the ability to store emails and blobs on Azure Blob Storage, alongside several minor fixes and improvements. As always, this release reflects our commitment to implementing the features most requested by our community.

Advanced Troubleshooting​

One of the key highlights of version 0.10.7 is the addition of comprehensive troubleshooting tools designed to help administrators diagnose and resolve email delivery and DMARC-related issues more efficiently.

The email delivery troubleshooting tool provides a step-by-step simulation of the email delivery process. Accessible through the Webadmin interface under Manage -> Troubleshoot -> Email Delivery, this tool allows administrators to test delivery paths for any email address or domain. It performs critical tasks like resolving MX records, retrieving IP addresses, validating MTA-STS and DANE policies, upgrading the connection to TLS, and verifying recipient availability. Importantly, this tool does not send actual emails but offers a detailed analysis of the delivery pipeline, displaying each step in real-time and flagging any issues that arise. This ensures that administrators can identify and address problems before they impact actual email traffic.

The DMARC troubleshooting tool is another powerful addition. Located under Manage -> Troubleshoot -> DMARC, it enables administrators to verify the DMARC setup for both local and remote domains. By simulating the server's authentication process, this tool checks SPF, DKIM, ARC, and DMARC policies while also verifying that the reverse PTR matches the SPF EHLO hostname. Administrators can input details such as the sender address, server IP, EHLO hostname, and optionally, the message body for detailed DKIM and ARC testing. This comprehensive tool mirrors the checks Stalwart performs when receiving emails, making it easier to identify and resolve policy compliance issues.

External Recipients​

Another significant enhancement in version 0.10.7 is the ability to add external recipients to mailing lists. In previous versions, mailing lists were restricted to local recipients, limiting their flexibility. With this update, administrators can now include recipients from external domains in mailing lists, enabling broader collaboration and more versatile email distribution. This change reflects our commitment to making Stalwart Mail Server more adaptable to the diverse needs of our users.

Azure Blob Storage​

In addition to the major feature updates, Stalwart Mail Server 0.10.7 introduces support for storing emails and blobs on Azure Blob Storage. This new capability provides users with greater flexibility in managing their data storage, especially for organizations already leveraging Azure's robust cloud infrastructure. The release also includes a range of minor fixes to improve overall stability and performance.

Looking Ahead​

As we celebrate the release of version 0.10.7, we are already working on the next major feature: faster and improved spam filtering. This enhancement, another highly requested feature, will bring more effective tools to combat unwanted emails while ensuring legitimate messages are processed efficiently. We are eager to share more details in the coming weeks.

Shape the Future​

Stalwart Mail Server continues to evolve based on feedback from our community. New features and improvements are implemented in the order of the votes they receive, ensuring that development aligns with the needs of our users. We invite you to visit our GitHub page to review the current list of enhancement requests and vote for the features you would like to see implemented next. You can find the list at GitHub Enhancement Requests.

Thank you for your ongoing support and feedback, which are instrumental in shaping Stalwart Mail Server into the reliable, user-focused solution it is today. We look forward to hearing your thoughts on version 0.10.7 and what you'd like to see in future releases!

We are happy to announce the release of Stalwart Mail Server v0.10.3, which introduces support for AI models —a powerful new feature now available to Enterprise Edition users as well as our GitHub and OpenCollective sponsors. With this feature, Stalwart Mail Server can be integrated with both self-hosted and cloud-based Large Language Models (LLMs), bringing advanced email processing capabilities like never before.

This integration allows you to use AI models for a variety of tasks, including enhanced spam filtering, threat detection, and intelligent email classification. Whether you choose to host your own models with LocalAI or leverage cloud-based services like OpenAI or Anthropic, this release provides the flexibility to incorporate cutting-edge AI into your email infrastructure.

Unlocking the Power of AI​

With the introduction of AI model integration, Stalwart Mail Server can now analyze email content more deeply than traditional filters ever could. For instance, in the realm of spam filtering and threat detection, AI models are highly effective at identifying patterns and detecting malicious or unsolicited content. The system works by analyzing both the subject and body of incoming emails through the lens of an LLM, providing more accurate detection and filtering.

In addition to bolstering security, AI integration enhances email classification. By configuring customized prompts, administrators can instruct AI models to categorize emails based on their content, leading to more precise filtering and organization. This is particularly useful for enterprises managing a high volume of messages that span various topics and departments, as AI-driven filters can quickly and intelligently sort messages into categories like marketing, personal correspondence, or work-related discussions.

The flexibility of using either self-hosted or cloud-based AI models means that Stalwart can be tailored to your infrastructure and performance needs. Self-hosting AI models ensures full control over data and privacy, while cloud-based models offer ease of setup and access to highly optimized, continuously updated language models.

LLMs in Sieve Scripts​

One of the most exciting features of this release is the ability for users and administrators to access AI models directly from Sieve scripts. Stalwart extends the Sieve scripting language by introducing the llm_prompt function, which allows users to send prompts and email content to the AI model for advanced processing.

For example, the following Sieve script demonstrates how an AI model can be used to classify emails into specific folders based on the content:

require ["fileinto", "vnd.stalwart.expressions"];

# Base prompt for email classification
let "prompt" '''You are an AI assistant tasked with classifying personal emails into specific folders. 
Your job is to analyze the email's subject and body, then determine the most appropriate folder for filing. 
Use only the folder names provided in your response.
If the category is not clear, respond with "Inbox".

Classification Rules:
- Family:
   * File here if the message is signed by a Doe family member
   * The recipient's name is John Doe
- Cycling:
   * File here if the message is related to cycling
   * File here if the message mentions the term "MAMIL"
- Work:
   * File here if the message mentions "Dunder Mifflin Paper Company, Inc." or any part of this name
   * File here if the message is related to paper supplies
   * Only classify as Work if it seems to be part of an existing sales thread or directly related to the company's operations
- Junk Mail:
   * File here if the message is trying to sell something and is not work-related
   * Remember that John lives a minimalistic lifestyle and is not interested in purchasing items
- Inbox:
   * Use this if the message doesn't clearly fit into any of the above categories

Analyze the following email and respond with only one of these folder names: Family, Cycling, Work, Junk Mail, or Inbox.
''';

# Prepare the base Subject and Body
let "subject" "thread_name(header.subject)";
let "body" "body.to_text";

# Send the prompt, subject, and body to the AI model
let "llm_response" "llm_prompt('gpt-4', prompt + '\n\nSubject: ' + subject + '\n\n' + body, 0.6)";

# Set the folder name
if eval "contains(['Family', 'Cycling', 'Work', 'Junk Mail'], llm_response)" {
    fileinto "${llm_response}";
}

This example demonstrates how the llm_prompt function can be used to classify emails into different categories such as Family, Cycling, Work, or Junk Mail based on the content. The AI model analyzes the message’s subject and body according to the classification rules defined in the prompt and returns the most appropriate folder name. The email is then automatically filed into the correct folder, making it easier to organize incoming messages based on their content.

Self-Hosted or Cloud-Based​

With this new feature, Stalwart Mail Server allows for seamless integration with both self-hosted and cloud-based AI models. If you prefer full control over your infrastructure, you can opt to deploy models on your own hardware using solutions like LocalAI. Self-hosting gives you complete ownership over your data and ensures compliance with privacy policies, but it may require significant computational resources, such as GPU acceleration, to maintain high performance.

Alternatively, you can integrate with cloud-based AI providers like OpenAI or Anthropic, which offer access to powerful, pretrained models with minimal setup. Cloud-based models provide cutting-edge language processing capabilities, but you should be aware of potential costs, as these providers typically charge based on the number of tokens processed. Whether you choose self-hosted or cloud-based models, Stalwart gives you the flexibility to tailor the AI integration to your specific needs.

Available for Enterprise Users and Sponsors​

This exciting AI integration feature is exclusively available for Enterprise Edition users as well as GitHub and OpenCollective monthly sponsors. If you want to harness the full potential of AI-powered email processing in Stalwart Mail Server, upgrading to the Enterprise Edition or becoming a sponsor is a great way to access this feature and other advanced capabilities.

Try It Out Today!​

The release of Stalwart Mail Server v0.10.3 marks a major milestone in our journey toward building intelligent, highly customizable email management solutions. By combining traditional email filtering with the power of LLMs, Stalwart gives you the tools to take your email infrastructure to the next level, enhancing security, organization, and automation in ways that were previously impossible. We’re excited to see how you’ll use this new feature to optimize your email workflows!

Today we announce the release of Stalwart Mail Server v0.10.2, and it’s a big one! This version brings full OpenID Connect (OIDC) support, empowering admins and developers to integrate secure authentication and single sign-on (SSO) with modern identity providers. In addition to OIDC, this release introduces OpenID Connect Dynamic Client Registration, OpenID Connect Discovery, and OAuth 2.0 Token Introspection. Let’s dive into what these features are and why they matter.

What is OpenID Connect?​

OpenID Connect (OIDC) is an identity layer built on top of OAuth 2.0 that allows clients to verify the identity of users. With OIDC, instead of just authorizing an app to access a resource, the system can also authenticate the user securely. This means users can log in to multiple applications with a single set of credentials, making OIDC ideal for Single Sign-On (SSO) across services.

Why is this important? Because it saves users from password fatigue, reduces login complexity, and centralizes authentication in a secure manner. Stalwart Mail Server’s new OIDC support allows you to authenticate your users either directly through Stalwart as an OpenID Provider or by integrating with third-party OIDC providers like Authentik, Keycloak, or any compliant identity system.

Alongside full OIDC support, Stalwart Mail Server v0.10.2 also introduces several important new features that expand its capabilities:

OpenID Connect Dynamic Client Registration​

Dynamic Client Registration allows clients (applications) to automatically register with the OIDC provider without requiring manual intervention. This feature makes it easier to integrate multiple applications, as clients can dynamically obtain credentials (like client IDs) directly from Stalwart Mail Server. This adds flexibility and reduces administrative overhead.

OpenID Connect Discovery​

With the OpenID Connect Discovery feature, clients can automatically discover the relevant OIDC endpoints and supported capabilities via the /.well-known/openid-configuration endpoint. This simplifies the configuration of OIDC clients, as they don’t need to be manually configured with URLs for token, authorization, and userinfo endpoints — they just query the discovery endpoint and set themselves up!

OAuth 2.0 Token Introspection​

OAuth 2.0 Token Introspection allows resource servers (like APIs or mail servers) to validate access tokens provided by clients. This ensures that the token being used is still active, hasn’t expired, and has the right permissions attached. This is particularly useful for securing interactions between various services while verifying that tokens are still valid.

OpenID Provider or Third-Party OIDC Support​

Stalwart Mail Server v0.10.2 can now act as an OpenID Provider (issuing ID tokens and managing authentication), which means your organization can use it to handle authentication for all your internal applications and services. Alternatively, Stalwart can also integrate with third-party OIDC providers, so you can delegate authentication to systems like Authentik or Auth0, while still using Stalwart to manage your email infrastructure.

This dual functionality gives you the flexibility to choose how you want to manage authentication while taking full advantage of OIDC's security features.

About OAUTHBEARER...​

Now, let’s talk about mail clients and the OAUTHBEARER SASL mechanism. While Stalwart fully supports OIDC, the majority of mainstream mail clients (looking at you, Outlook, Thunderbird, and Apple Mail) still don’t support OAUTHBEARER for OAuth-based authentication. Sure, we’ve done our part by adding OpenID support to Stalwart — now it's up to the mail clients to follow suit and add proper support for OIDC authentication. Maybe one day, we’ll see these clients finally catch up, and we can all enjoy the seamless authentication experience that OIDC offers.

In the meantime, users of these clients will need to continue using App Passwords to access their email accounts. But hey, maybe this is the gentle nudge the developers of these clients need to jump on the OpenID bandwagon!

Try It Out​

Stalwart Mail Server v0.10.2 is available now, so download it, upgrade your server, and start taking advantage of these new features! Whether you’re setting up Stalwart as your OpenID Provider or integrating with a third-party provider, this release gives you the tools to secure authentication with modern standards like OpenID Connect.

Happy mailing and happy authenticating!

We are happy to announce that Stalwart Mail Server 0.10.0 is officially here! This latest release brings some exciting new features to help you manage your email infrastructure more effectively. With multi-tenancy, branding, and a robust roles and permissions system, Stalwart is more powerful and flexible than ever before. Let’s dive into what’s new in this release!

Multi-Tenancy: Streamlined Management​

Multi-tenancy is a game-changer for anyone managing multiple independent organizations on a single instance of Stalwart Mail Server. Whether you’re a hosting provider or an enterprise with multiple departments, tenants allow you to isolate different organizations, each with its own users, groups, mailing lists, and domains.

Each tenant operates within its own secure space, ensuring privacy and separation from other tenants. You can assign disk quotas to control how much storage each tenant can use and limit the number of accounts, groups, and domains they can create. This is perfect for keeping resources in check while maintaining an organized, scalable environment. Imagine a scenario where a tenant is given 100GB of disk space. If the users within that tenant collectively consume all 100GB, the system prevents them from receiving more email, ensuring no one overuses resources.

Multi-tenancy offers security, control, and scalability—all in one package.

Roles & Permissions: Fine-Tuned Access Control​

With the revamped Roles and Permissions system, Stalwart Mail Server 0.10.0 gives you unprecedented control over who can do what in your environment. No more blanket admin accounts! Instead, you can assign specific permissions to individuals, groups, or entire tenants.

Permissions can be bundled into roles, which makes managing access a breeze. Stalwart comes with three built-in roles to get you started: the user role, which grants access to all essential email services; the admin role, which has full control over the system; and the tenant-admin role, which is perfect for tenant or domain administrators, providing just the right amount of access without overstepping into critical system configurations.

This granular permissions model ensures that no one has more access than they need, keeping your system secure while allowing users to perform their required tasks. Whether it’s managing users, updating settings, or overseeing mailing lists, the right permissions are always in the right hands.

Branding: Personalized Web Interface​

Another exciting new feature in Stalwart Mail Server 0.10.0 is branding. This feature allows system administrators to customize the look and feel of the webadmin interface by adding logos specific to each tenant or domain.

When a user logs into the webadmin portal, Stalwart checks the domain associated with the request. If a logo has been set for that domain, it will be displayed. If the domain doesn’t have its own logo but is linked to a tenant that does, the tenant’s logo will be used. If neither the domain nor the tenant has a custom logo, the system defaults to the logo defined in the configuration. If no logo is defined, the trusty Stalwart logo makes an appearance. This feature ensures that your tenants can enjoy a fully branded experience, making the platform feel even more tailored to their organization.

Enterprise-Only Features: Multi-Tenancy & Branding​

It’s important to note that while Roles and Permissions are available in all versions of Stalwart Mail Server, the Multi-tenancy and Branding features are part of the Enterprise package. These advanced tools are designed for organizations with more complex needs, providing flexibility and customization options tailored to large-scale environments.

Support Stalwart: It Costs Less Than Netflix!​

We’ve worked hard to keep Stalwart open and accessible to everyone, but if you want to unlock Enterprise features and support the continued development of Stalwart, please consider subscribing to a Stalwart Enterprise License. It costs less than your Netflix or Spotify Premium subscription and will help us continue building exciting new features, including upcoming developments like CalDAV, CardDAV, WebDAV, and JMAP for contacts, calendars, and tasks.

By subscribing, not only do you unlock advanced functionality, but you also contribute to the growth of a project committed to providing a powerful, open mail server solution for all.

Thank you for being part of the Stalwart community. We hope you enjoy these new features as much as we enjoyed building them, and we look forward to bringing you even more great updates in the future. If you’re interested in learning more about Stalwart Enterprise or obtaining a license, feel free to reach out to us.

Happy mailing!

We're excited to announce the release of Stalwart Mail Server version 0.9.3! Whether you're using the Community or Enterprise version of Stalwart Mail Server, this update brings powerful new features to enhance your email infrastructure's security, performance, and monitoring capabilities. Let's dive into what's new:

Comprehensive Dashboard​

A major highlight of this release for Enterprise users is the introduction of the new Dashboard feature. This tool provides real-time insights into your server's operations, allowing you to monitor critical metrics and trends at a glance. The Dashboard is divided into five distinct sections: Overview, Network, Delivery, Security, and Performance. The Overview dashboard offers a comprehensive summary of general mail server statistics, giving you a quick snapshot of the server's health and activity. The Network dashboard focuses on the number of total and active connections, enabling you to monitor network traffic and identify potential issues with server load. The Delivery dashboard provides detailed information on mail flow, including queued messages and the number of messages sent and received, ensuring that your mail delivery processes are running smoothly. The Security dashboard is dedicated to tracking your server’s defenses, presenting statistics on banned IPs, blocked requests, and spam filtering effectiveness. Finally, the Performance dashboard allows you to monitor key performance indicators such as memory usage, database latency, and DNS latency, helping you optimize the server's performance and address any bottlenecks.

Customizable Alerts​

Also new to the Enterprise version is the Alerts feature, which ensures that you are always in the loop when important metrics reach critical thresholds. Whether it's a spike in memory usage, an increase in queued messages, or any other significant change, Alerts can notify you via email or webhooks the moment these events occur.

Alerts are highly configurable, allowing you to set up complex conditions that trigger notifications only when specific combinations of metrics are met. For example, you could set an alert for when server memory usage exceeds a certain amount and the message queue count rises above a defined level, helping you to react swiftly and prevent potential disruptions.

Security Enhancements​

Security remains a top priority in this release, and version 0.9.3 introduces two new features that enhance the defenses of both the Community and Enterprise versions.

RCPT Brute Force Protection​

Enhance your server's security with our new RCPT brute force protection. This feature automatically bans IP addresses attempting to discover valid email recipients through brute force attacks—a common tactic used by spammers. By implementing this protection, Stalwart Mail Server adds another layer of defense to your email infrastructure, helping to maintain the integrity of your user list and prevent potential security breaches.

Loitering Connection Protection​

Defend against SYN Flood attacks with our loitering connection protection. This smart feature blocks IP addresses that repeatedly keep connections open without meaningful activity, helping to prevent resource exhaustion attacks. By identifying and mitigating these potential threats, Stalwart Mail Server ensures that your server resources are used efficiently and remain available for legitimate email traffic.

Conclusion​

Stalwart Mail Server version 0.9.3 is a significant step forward in our commitment to providing a secure, efficient, and easy-to-manage mail server solution. Whether you are leveraging the powerful new monitoring and alerting tools in the Enterprise version or benefiting from the enhanced security features available across both versions, this update offers valuable enhancements that will help you better manage and protect your mail server.

We encourage all users to upgrade to version 0.9.3 and take advantage of these exciting new features. As always, we remain dedicated to improving Stalwart Mail Server and providing you with the best possible tools to manage your email infrastructure.

Thank you for your continued support, and we look forward to bringing you more updates and features in the future!

We are thrilled to announce the release of Stalwart Mail Server version 0.9.1, which comes packed with significant enhancements to our telemetry capabilities. This release marks a major milestone in our ongoing efforts to provide robust and efficient monitoring and logging solutions, ensuring our users can achieve optimal server performance and reliability.

Enhanced Tracing​

In previous versions of Stalwart, tracing and logging provided valuable insights but lacked the detail and comprehensiveness needed for thorough monitoring. With version 0.9.1, we have completely rewritten the tracing and logging layer, resulting in a faster and more detailed system. The new implementation leverages a lock-free data structure, enabling Stalwart to record thousands of events per second without impacting server performance. This major upgrade ensures that every significant event is captured, providing a comprehensive view of the server's operations.

Stalwart now generates over 600 different types of events, significantly expanding the granularity and depth of our telemetry data. These events can be sent to OpenTelemetry or Webhooks, offering flexibility in how they are processed and analyzed. Additionally, events can be recorded in log files, sent to journald, or written directly to the console, providing multiple avenues for accessing and utilizing this detailed information.

Comprehensive Metrics​

The highlight of Stalwart Mail Server version 0.9.1 is the introduction of support for hundreds of different metrics. This enhancement enables administrators to gain deeper insights into the server's performance and health. Metrics can be exported to OpenTelemetry using a push mechanism, allowing for real-time monitoring and analysis. Alternatively, they can be collected using Prometheus via a pull method, integrating seamlessly with existing monitoring infrastructures.

This robust metrics support ensures that users can monitor a wide range of server parameters, from resource usage to request handling, enabling proactive maintenance and troubleshooting. By providing comprehensive metrics, Stalwart Mail Server empowers administrators to make informed decisions, optimize performance, and maintain high levels of reliability.

HTTP Access Controls​

In addition to these telemetry improvements, Stalwart Mail Server version 0.9.1 introduces a highly requested feature: HTTP endpoint access controls. This new capability allows administrators to limit access to HTTP endpoints based on various criteria, such as remote IP or IP range, HTTP method, listener ID, and more. This fine-grained control enhances security and ensures that only authorized users can access specific server functionalities.

The introduction of HTTP endpoint access controls responds directly to user feedback, demonstrating our commitment to continually enhancing the server based on real-world needs and experiences. This feature provides an additional layer of security and customization, making Stalwart Mail Server more versatile and robust.

Conclusion​

Stalwart Mail Server version 0.9.1 represents a significant leap forward in our telemetry capabilities, offering faster, more detailed tracing and logging, comprehensive metrics support, and new HTTP endpoint access controls. These improvements underscore our dedication to providing a powerful, efficient, and secure mail server solution.

Upgrade to version 0.9.1 today and experience the next level of telemetry with Stalwart Mail Server!

We are excited to announce a partnership between Stalwart Labs and Nextcloud, bringing together our state-of-the-art Stalwart Mail Server with the comprehensive Nextcloud suite. This collaboration marks a significant step forward in enhancing productivity, security, and user experience for our customers.

What This Means for You​

Nextcloud will now also offer a version bundled with Stalwart Mail Server, providing users with a powerful, efficient, and secure email solution seamlessly integrated within the Nextcloud environment. This integration is designed to provide a cohesive and streamlined experience, allowing users to manage their email, files, and collaborative projects all in one place.

Key Benefits​

• Enhanced Productivity: With Stalwart Mail Server bundled into Nextcloud, users can effortlessly access their email and other Nextcloud apps, such as files, calendars, and tasks. This unified approach reduces the time and effort spent on managing multiple platforms.
• Robust Security: Both Stalwart Labs and Nextcloud prioritize security. Our mail server brings industry-leading security features, including encryption and advanced threat detection, ensuring your communications remain safe and confidential.
• Seamless Collaboration: Nextcloud is known for its powerful collaboration tools. Integrating Stalwart Mail Server enhances these capabilities, allowing for better coordination and communication within teams.
• User-Friendly Interface: Our combined efforts focus on delivering an intuitive and user-friendly interface, making it easier for users to navigate and utilize the full potential of the integrated suite.

About Stalwart Mail Server​

Stalwart Mail Server is a highly reliable and secure email server designed for modern businesses. With features such as spam filtering, encryption, and high availability, it provides an unparalleled email experience. Our server is built to handle the demands of any organization, ensuring your communications are always fast, reliable, and secure.

About Nextcloud​

Nextcloud is the leading open-source software suite for file sharing and collaboration. It offers a wide range of tools for managing and sharing files, calendars, contacts, and more, all while maintaining the highest standards of security and privacy. Nextcloud is trusted by millions of users worldwide, from small businesses to large enterprises.

Looking Ahead​

This partnership is just the beginning. We are committed to continuously improving and expanding our integrated solutions to meet the evolving needs of our users. Stay tuned for more updates and enhancements as we work together to bring you the best in productivity and security.

We invite you to explore the new integrated experience and see firsthand how Stalwart Mail Server and Nextcloud can transform the way you work. For more information, please visit our website or contact our team.

Thank you for your continued trust and support.