The director shall have the general charge and supervision of the central mailing office, and shall be responsible for its efficient administration. The director shall be required to: (1) Charge each spending unit of state government served by the central mailing office for providing such services; (2) keep proper account of the receipts and disbursements of the central mailing office; (3) render to the secretary a report each month showing the receipts and expenses of the central mailing office for the preceding month, and shall render such other reports as the secretary may require; (4) keep the central mailing office open during regularly stated hours to serve state spending units; and (5) provide rules and regulations for the efficient and prompt dispatch of the mail.