e-mail filter for spam that learns

 A small, fast, flexible Bayesian filter for processing e-mail. It is
 "trained" by the user to categorize email as spam or non-spam. This
 implementation integrates well with existing tools such as procmail
 and mutt. It can use a variety of formats for storing data. A utility
 is supplied for converting data between the supported formats.
 .
 This package includes support for text and libdb formats.
 .
 See "A Plan for Spam" <https://www.paulgraham.com/spam.html> by Paul Graham
 for further information.