Stopping spam mails on individual desktops is probably best done through some solution that uses Bayesian or statistical filtering. This is a way of stopping spam by using statistical analysis, rather than white or blacklisting, to determine what mail is legitimate. Symantec AntiSpam, Outlook 2003, or Netscape's new mailbox all use Bayesian techniques in combination with other methods.
One of the best free solutions is SpamBayes (spambayes.sourceforge.net), which integrates directly with Outlook or works with any POP3-compatible email client to stop spam.
Microsoft also has a plugin for Exchange that combats spam based on statistics and rules generated by analyzing millions of emails filtered through Hotmail.
This was first published in November 2003