Mail filtering

Overview Message filtering is done prior to delivery via maildrop. Each message goes through two levels of filters: (1) global — processed first in /etc/maildroprc followed by (2) local per-user filters in $HOME/.mailfilter. Basic filtering recipes are provided below. Syntax and usage may be found in mailfilter(7). Important: on older platforms, (less than v6), remember to…

Improving mail filter performance

Overview E-mail that flows into the server goes through several phases of filtering before final delivery, including: DNSBL lookups on handshake Deep protocol inspection DomainKeys/SPF validation SpamAssassin filtering Whitelist management Hash-sharing systems (DCC & Razor) Token-based regex matching Markup filtering Bayesian filtering All steps in the filtering process are automated, except for Bayesian filtering that works by…