clapf is an email content filter application. It includes a statistical (inverse chi-square) anti-spam module, interfaces to several anti-virus products, a minefield (blackhole), spam quarantine, support for various RBL lists, training utilities, and much more. It can be used as an after queue content filter with Postfix (including as an appliance) or via a local delivery agent (LDA), preferably maildrop.
License: zlib/libpng License
Changes:
A timestamp field was added to the tokens table so that you can purge aged entries. Virus infected emails are silently discarded. The attachment analysis code was removed. LMTP/SMTP local delivery support was added. A smarter configure script and Makefile were provided along with whitelist and blacklist support and an auto-learning feature. Messages are stored in a per-user directory (not in SQL). Retraining went to clapf and spamdrop. The blackhole/minefield is handled by spamdrop. XFORWARD extension support was added to catch DHA attacks. Administrative support was provided in spam quarantine. Training is handled by spamdrop.