A method for filtering incoming data from an external computer network is provided. This method includes scanning the contents of incoming data for pre-selected keyword(s) and allowing it to pass per standard service rules if its content does not contain the pre-selected keyword(s). If the incoming data does contain pre-selected keywords, it is blocked and added to a "known-block" filtering table. Once added to the filtering table, the site will automatically be blocked in the future without having its contents scanned again for pre-selected keywords.