Rspamd 4.0.0 ships memory savings, a new scan protocol, and a required migration step The open-source spam filtering platform Rspamd released version 4.0.0, delivering infrastructure changes across its scan protocol, memory model, hash storage, and configuration system. Several of the changes are breaking, and at least one requires a migration step before upgrade. A new scan protocol The release introduces a /checkv3 endpoint that replaces HTTP headers with structured JSON or msgpack for metadata transport. The new endpoint uses multipart/form-data for requests and multipart/mixed for responses, supports per-part zstd compression, includes an optional body part for rewritten messages, and uses zero-copy piecewise writev for response output. Operators can activate the new protocol with the…