In fiscal year 1991 and thereafter, when a Senator disseminates information under the frank by a mass mailing (as defined in section 3210(a)(6)(E) of title 39), the Senator shall register quarterly with the Secretary of the Senate such mass mailings. Such registration shall be made by filing with the Secretary a copy of the matter mailed and providing, on a form supplied by the Secretary, a description of the group or groups of persons to whom the mass mailing was mailed and the number of pieces mailed