Except as provided under chapters 2 and 12 of this title,
section 415 of title 5, or other provision of law, the Postal Service shall classify and fix the compensation and benefits of all officers and employees in the Postal Service. It shall be the policy of the Postal Service to maintain compensation and benefits for all officers and employees on a standard of comparability to the compensation and benefits paid for comparable levels of work in the private sector of the economy. No officer or employee shall be paid compensation at a rate in excess of the rate for level I of the Executive Schedule under
section 5312 of title 5.