bogofilter

Bogofilter is or can be integrated with graphical mailers, such as KDE's KMail, GNOME's Evolution or Claws Mail (formerly known as Sylpheed-Claws), or it is run by a mail delivery agent (maildrop, procmail) script to classify an incoming message as spam or ham (using wordlists stored by BerkeleyDB). Bogofilter provides processing for plain text and HTML. It supports multi-part MIME messages with decoding of base64, quoted-printable, and uuencoded text and ignores attachments, such as images.