Cactus Spam Filter is a free easy-to-use spam blocker. It protects your inbox by learning to detect spam as it's being used. After a short while it has adapted to your personal mailbox and blocks out most of the junk e-mail. This spam stopper integrates seamlessly with all e-mail clients that use POP3 such as Microsoft Outlook, Microsoft Outlook Express, Netscape, Opera, Mozilla, Eudora, IncrediMail, Pegasus Mail, Foxmail and Phoenix Mail.