No publisher, radio-broadcast licensee, or agency or medium for the dissemination of an advertisement, except the manufacturer, packer, distributor or seller of the article to which a false advertisement relates, shall be liable under this section [act] by reason of dissemination by him of such false advertisement, unless he has refused, on the request of the board, to furnish the board the name and post-office address of the manufacturer, packer, distributor, seller or advertising agency, who cause [caused] him to disseminate such advertisement.