1. A system for updating filtering rules for messages received by a plurality of users, the system comprising: a filtering rules database storing filtering rules for the plurality of users; means for distributing the filtering rules to the plurality of users; a user reputation database comprising a reputation weight for each of the plurality of users; and means for receiving and processing of user reports that indicate that a message belongs to a particular category, wherein the means for receiving (i) calculates a message weight in its category based on a number of reports received from multiple users and a reputation weights of those users, (ii) decides whether the message belongs to the particular category if the message weight exceeds a predefined threshold, (iii) updates the filtering rules in the filtering rules database based on the deciding, and (iv) distributes the updated filtering rules from the filtering rules database to the plurality of users using the means for distributing.