Rspamd
Fast open source spam and phishing filtering system for Postfix, Exim, and Sendmail.
Technical Architecture & Overview
Rspamd is a high-performance filtering system written in C with Lua extension support. It evaluates messages through SPF, DKIM, DMARC, and ARC checks, DNS blocklists, greylisting, statistical classifiers, and content rules, then applies a combined score. The engine has run in production since 2008 and integrates with major MTAs through milter or native protocols. Optional commercial plans exist alongside the open source core.
Targeted Technical Use Cases
Self-hosted mail platforms that need a maintained filtering engine with tunable scoring.
Evaluation & Trade-offs
Core Strengths
- +High throughput compared to Perl-based alternatives.
- +Extensible rule and plugin system in Lua.
- +Full protocol check coverage including DMARC and ARC.
Trade-Offs & Limitations
- -Requires operating the surrounding mail infrastructure.
- -Tuning symbol scores takes experience.
Defensive Security Application
Filtering inbound mail for self-hosted domains without routing mail through a third-party gateway.
Frequently Asked Questions
What is Rspamd?→
Rspamd is a high-performance filtering system written in C with Lua extension support. It evaluates messages through SPF, DKIM, DMARC, and ARC checks, DNS blocklists, greylisting, statistical classifiers, and content rules, then applies a combined score. The engine has run in production since 2008 and integrates with major MTAs through milter or native protocols. Optional commercial plans exist alongside the open source core.
What is Rspamd used for?→
Self-hosted mail platforms that need a maintained filtering engine with tunable scoring.
What are the strengths of Rspamd?→
- +High throughput compared to Perl-based alternatives.
- +Extensible rule and plugin system in Lua.
- +Full protocol check coverage including DMARC and ARC.
What are the limitations of Rspamd?→
- +Requires operating the surrounding mail infrastructure.
- +Tuning symbol scores takes experience.
How is Rspamd used defensively?→
Filtering inbound mail for self-hosted domains without routing mail through a third-party gateway.