SpamAssassin is a computer program released under the Apache License 2.0 used for e-mail spam filtering based on content-matching rules, which also supports DNS-based, checksum-based and statistical filtering, supported by external programs and online databases. SpamAssassin is regarded by some as one of the most effective spam filters, especially when used in combination with spam databases. While simple text-matching alone may, for most users, be sufficient to correctly classify a majority of… (More on Spamassassin)