Due to its Bayesian nature, K9 doesn't look at and filter your mail using a predefined set of rules. Instead, it learns from you what you think is spam.

This is why K9 won't detect much spam (none, actually) if you've just begun using it, and it will make mistakes. If you correct these mistakes — which is really a must —, K9 learns with each correction and the mistakes will become less and less frequent.

Fortunately, K9 learns very fast and, fortunately, it's easy to correct a misclassifications on K9's part.

Teach K9 What is Spam and What is Good Mail

To tell K9 what is spam and what is good mail if K9 got a message's spam score wrong:

• Go to the Recent Emails tab.
• Highlight the wrongfully classified message.
  • You can highlight more than one message by holding down Ctrl while clicking.
  • The messages retrieve during the most recent mail check will be bold.
• Click Good or Spam to teach K9 about the highlighted messages.