Rspamd 4.2.1: Patch the Filter, Then Check What It Actually Does

An email filter should spend its time judging messages, not falling over while reading them. Rspamd’s latest patch is a reminder that the machinery around spam scoring deserves attention too. The official release index dates Rspamd 4.2.1 to October 1, 2026. That makes it fresh news for this week’s maintenance list. Our earlier article covered 4.1.0; this update has a different practical angle: check the filter’s health and configuration, rather than reaching immediately for more permissive spam thresholds. ...

October 5, 2026 · 4 min

Rspamd 4.1.0: Security Fixes, a Reworked MX Check, and a Breaking Symbol Rename

Rspamd 4.1.0 dropped on June 5 — a major release tagged “recommended upgrade for all users” by the development team. There’s enough in it that’s immediately relevant to anyone running a mail server to warrant reading the changelog before blindly upgrading. The security fixes This release addresses several memory-safety issues that can be triggered by crafted incoming mail. S/MIME DoS via recursive PKCS7: A deeply nested application/pkcs7-mime message re-entered the parser without incrementing the nesting counter. In practice this means a malicious sender could craft a message that exhausts your rspamd worker’s stack. The fix gates S/MIME re-entry against the existing max_nested limit. ...

June 7, 2026 · 3 min