In a report required by the Can-Spam Act, the Federal Trade Commission has told Congress that an "ADV" label requirement for the subject lines of commercial emails would not help consumers or internet service providers, AdWeek reports. As it had in an earlier report on the establishment of a do-not-spam registry, the FTC said most spammers would not heed such a requirement. It said ISPs' spam filters are already more effective than a largely unheeded label would be. The FTC has preferred enforcement, education of consumers and businesses, and development of email authentication and reputation-systems to reduce spam.