May 26, 2018
SpamAssassin is a mail filter which attempts to identify spam using text analysis and several internet-based realtime blacklists.
Using its rule base, it uses a wide range of heuristic tests on mail headers and body text to identify “spam”, also known as unsolicited commercial email.
Once identified, the mail can then be optionally tagged as spam for later filtering using the user’s own mail user-agent application.
Additional drop-in rule sets are available at http//wiki.apache.org/spamassassin/CustomRulesets