mail relating to naturalization transmitted free of postage and registered

mail relating to naturalization transmitted free of postage and registered Sec. 345. All mail matter of whatever class, relating to naturalization, including duplicate papers required by law or regulation to be sent to the Service by clerks of courts addressed to the Department of Justice or the Service, or any official thereof, and endorsed “Official Business”, shall be transmitted free of postage and, if necessary, by registered mail without fee, and so marked.