Stamps to be defaced

§ 2507. Stamps to be defaced (a) The Postmaster General shall direct the manner in which postage stamps on mail matter shall be canceled and may furnish necessary equipment and supplies therefor. (b) The Postmaster General may furnish to post offices postage stamps precanceled with the name of the post office at which they are to be used imprinted thereon. (c) The Postmaster General may issue permits to persons using stamped envelope and postal cards to precancel the postage stamps thereon.