Section 157(2) in The Haryana Motor Vehicles Rules, 1993
(2)A public service vehicle when regularly used for carrying Government mail by or under a contract with the Indian Posts and Telegraphs Department shall exhibit in conspicuous place upon a flat or a plane, surface of the vehicle the words 'MAIL' in red on the white ground, each letter being not less than 100 millimetres, in height and of a uniform thickness of 20 millimetres.
