Indian Post Office Act, 1898
37. Power to make rules as to disposal of undelivered postal articles
(1) The Central Government may make rules as to the disposal of postal articles which for any reason cannot be delivered (hereinafter referred to as "undelivered postal articles").
(2) In particular and without prejudice to the generality of the foregoing power, such rules may-
(a) prescribe the period during which undelivered postal articles at a post office shall remain in that office; and
(b) provide for the publication of lists of undelivered postal articles, or of any class of undelivered postal articles.
(3) Every undelivered postal article, after being detained at a post office for the period prescribed by rule under the foregoing provisions of this section, shall be either forwarded, free of further charge, to the post office at which it was posted, for return to the sender, or sent to the office of the Post Master General.