Beginning July 1, 1943, all official outgoing mail of each state officer, department, commission, board, bureau, court or other agency, occupying quarters in the Capitol Building in Lincoln, Nebraska, or in any state building which may hereafter be located adjacent thereto, shall be delivered unstamped to such central mailing room to be metered and dispatched; Provided, however, members of the Legislature shall be specifically exempt from the provisions of sections 81-164 to 81-171 for and during the time the Legislature is not in actual session. All employees of such state officers, departments, commissions, boards, bureaus, courts or other agencies, when working away from the Capitol Building, shall use the metered mail for outgoing mail so far as may be possible, consistent with postal regulations.