Apache SpamAssassin vs PreciseMail Anti-Spam Gateway

Apache SpamAssassin is free, open-source software that classifies email to help system administrators block unsolicited bulk messages. It runs on a server to filter mail before it reaches a mailbox. Detection combines header and text analysis, Bayesian filtering, DNS blocklists, collaborative filtering databases, and local and network tests. Its scoring framework and plugins add heuristic and statistical checks. Tests and configuration are stored as plain text, so administrators can adjust settings and add rules. The Mail::SpamAssassin API can be integrated with systems such as procmail, sendmail, Postfix, and qmail. The core distribution includes command-line filtering tools and Perl modules for use in other products. The downloads page lists version 4.0.2 as the released version. Official releases are signed, with GPG signatures and SHA-256 and SHA-512 checksum links for downloads. Users can ask questions on the mailing list; developers and PMC members answer as time permits.

PreciseMail Anti-Spam Gateway has no write-up on Specifiction yet; its figures are above.