Section 46A(1) in The Indian Post Office Rules, 1933
(1)No article shall be transmitted by post which has anything written, printed or otherwise impressed upon or attached to its address-side, which, either on account of its being likely to be mistaken for stamps used for the payment of postage or by inconvenient proximity to any such stamp or by tending to prevent the easy and quick reading of the address or in other way, is in itself or in the manner in which it is written, printed, impressed or attached, likely, in the opinion of the Director General, to embarrass the officers of the Post Office in dealing with such article.
