Mail classification that never leaves your network.
PDMSC is a cascade of small, specialised models. Cheap, precise layers settle most mail early; the expensive layers only see what survives. It runs beside your existing rspamd on hardware you already own, with no per-seat metering and no message content sent to anyone.
01What PDMSC does
Decide early, defer when unsure
The current English set is nine models arranged as a cascade, each able to decide or defer. Peer groups require agreement before a single specialist can act alone.
Undecided is an answer
Mail the cascade cannot score, through no detectable language or too little text, is returned as undecided rather than guessed at. The surrounding rspamd signals decide it.
Drops in beside rspamd
PDMSC is an external_services backend over HTTP. It can run in observe-only mode first, scoring live mail at zero weight so you see what it would have done before it decides anything.
Runs on what you have
FreeBSD, OpenBSD, BSDSUniX, Linux and Solaris 10, on AMD64, Intel, ARM64 and SPARC64, on bare metal, virtual machines, or logical domains.
Language sets load independently
The on-disk format is structural rather than fixed to one shape. Language sets sit alongside one another and load independently.
Fails open, never blocks mail
If the classifier stops for any reason, the verdict is neutral and mail flows on unfiltered. A licence problem can stop the classifier; it can never stop your mail.
02How we measure
Every figure on this page comes from the real daemon on production hardware, not from an offline scoring harness, because offline replay reads about 4% optimistic here. Rates are over messages the cascade can score, and that exclusion is stated rather than folded into the percentage. Test messages are checked by hand before a result is believed; one message counted against the engine in an earlier run turned out to be spam that had been filed as legitimate. Figures are dated August 2026 and are reproducible on request, including on your own mail.
03Part of a larger stack
See what it would have done with your mail.
Tell us about your rspamd deployment and we will scope an observe-only pilot on your existing infrastructure.