spamassassin - 4.0.0-6 main

SpamAssassin is a very powerful and fully configurable spam filter
with numerous features including automatic white-listing, RBL
testing, Bayesian analysis, header and body text analysis. It is
designed to be called from a user's .procmail or .forward file, but
can also be integrated into a Mail Transport Agent (MTA).
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If you use spamassassin on a moderately high-volume mail server, you
may which to consider installing the spamc and spamd packages, which
provide a daemonized variant of spamassassin that avoids the need to
start a full perl runtime for each message processed.