The present invention provides systems, methods, computer program products, and combinations and subcombinations thereof for filtering received messages. The invention includes a client system having filtering logic, a statistical classifier module, and a classifier database. The classifier module is automatically trained, without manual intervention, when the score generated by the classifier for a received message is inconsistent with a user-defined authoritative status indication. In addition, the classifier module is initialized using user-identified messages in a ratio representative of the ratio of non-spam to spam messages received by the user.