Advanced spam and phishing protection

Shield your inbox with Stalwart, keeping your emails safe from threats and intrusions.

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Efficient filtering

Fast and reliable filtering for today's threat landscape.

Stalwart's spam and phishing filters provide robust protection that rivals the most popular solutions in the market, featuring a comprehensive set of filtering rules to keep your inbox clean and secure. Unlike other spam filters, which can slow down message delivery due to their heavy reliance on regular expressions, Stalwart's built-in filters operate at a significantly faster pace. This is because everything is integrated and optimized within the system itself, eliminating the need for repetitive checks and excessive parsing typically encountered when using external filtering solutions. With Stalwart, you get speedy and efficient email filtering without the usual overhead, ensuring your communications are both swift and secure.

AI-enhanced filtering

Harness AI for unmatched spam and phishing defense.

Stalwart's spam and phishing filtering capabilities harness the power of AI to provide unparalleled protection for your email environment. The open-source edition of Stalwart features a robust statistical spam classifier that learns and adapts automatically, enhancing its effectiveness over time. For organizations seeking even more advanced filtering, the enterprise version takes this a step further by integrating AI-powered spam and phishing defenses. This version allows seamless connectivity with leading AI providers like OpenAI and Anthropic, as well as compatibility with self-hosted large language models like Llama. With these cutting-edge technologies, Stalwart ensures that your inbox remains secure against the most sophisticated threats, all while maintaining swift and accurate filtering.


DNSBL support

Enhanced email defense with extensive screening.

Stalwart takes email security to the next level with its comprehensive DNS Blocklists (DNSBLs) integration. In addition to checking the sender IP addresses against DNSBLs, Stalwart goes further by scrutinizing every single email address, URL, and domain mentioned within the message contents. This thorough approach ensures that even the most subtle threats are detected and blocked, providing robust protection against spam and malicious content. By leveraging DNSBLs extensively, Stalwart significantly enhances your email security, keeping your inbox safe from a wider range of potential threats.

Digest-Based Filtering

Boost spam detection with collaborative filtering.

Stalwart enhances its spam filtering capabilities with collaborative digest-based spam filtering, a powerful technique that improves detection accuracy by leveraging shared information about known spam across multiple sources. This method involves creating digests of email content and comparing them against a database of known spam digests, effectively identifying and blocking unwanted messages. Stalwart supports this advanced filtering approach right out of the box and integrates seamlessly with databases like Pyzor. This integration ensures that your email environment benefits from collective intelligence, providing robust protection against spam and keeping your inbox clean and secure.



Guarding your inbox from deceptive phishing tactics.

Stalwart provides robust phishing protection, designed to guard against various sophisticated phishing techniques, including homographic URL attacks and sender spoofing. Homographic URL attacks involve using visually similar characters to deceive users into clicking on malicious links that appear legitimate. Sender spoofing, on the other hand, involves forging the sender's address to make an email appear as if it comes from a trusted source. Stalwart's comprehensive phishing protection detects and mitigates these threats, ensuring your email communications remain secure and trustworthy. By leveraging advanced detection mechanisms, Stalwart effectively shields your inbox from deceptive tactics and enhances overall email security.

Reputation monitoring

Proactive spam defense with reputation tracking.

Stalwart takes email security a step further with its sophisticated sender reputation monitoring system. By tracking the reputation of senders based on IP address, ASN, domain, and email address, Stalwart ensures a proactive approach to spam prevention. The system automatically adjusts spam scores according to the monitored sender reputation, effectively filtering out suspicious emails and enhancing the accuracy of spam detection. This dynamic adjustment mechanism helps maintain a clean and secure inbox, providing robust protection against unwanted and potentially harmful emails.


Reply tracking & greylisting

Effective handling of genuine senders and unknown sources.

Stalwart incorporates advanced features to enhance email handling and security. One such feature is trusted reply tracking, which ensures that genuine email replies are recognized and prioritized, preventing them from being misclassified as spam. Additionally, Stalwart employs greylisting, a technique that temporarily defers emails from unknown senders, giving legitimate servers the chance to resend while deterring spam bots. These combined capabilities help maintain the integrity of your inbox by accurately identifying authentic communications and effectively managing unknown sources.

Spam traps

Refining spam filtering with targeted spam traps.

Stalwart employs advanced spam trap features to enhance its spam filtering capabilities. Spam traps, also known as honey pots, are email addresses specifically created to attract and identify spam. These addresses are not used for any legitimate communication, so any email they receive is automatically considered spam. Stalwart leverages these spam traps to automatically train its spam classifier, improving its accuracy and effectiveness over time. By analyzing the messages caught in the spam traps, Stalwart continuously refines its filtering algorithms, ensuring robust protection against unwanted and malicious emails.