Ricochet is an automated agent for tracing and reporting  internet  junk
    mail (a.k.a Spam). Ricochet analyses the headers of a spam  to  identity
    the machines used for its injection, looks up the email addresses of the
    machine owners and mails out a complaint to them. Ricochet uses  various
    network information resources like nameserver records,  MX  records  and
    Whois databases worldwide to collect and verify this information.

WWW: http://www.vipul.net/ricochet/