21. Power to make rules as to transmission by post of postal articles.- (1) The Central Government may make rules as to the transmission of articles by post. (2) In particular and without prejudice to the generality of the foregoing power, such rules may- (a) specify articles which may not be transmitted by post; (b) prescribe conditions on which articles may be transmitted by post; (c) provide for the detention and disposal of articles in course of transmission by post in contravention of rules made under clause (a) or clause (b); (d) provide for the granting of receipts for, and the granting and obtaining of certificates of, posting and delivery of postal articles and the sums to be paid, in addition to any other postage, for such receipts and certificates; and (e) regulate covers, forms, dimensions, maximum weights, and enclosures, and the use of postal articles, other than letters, for making communications. (3) Postal articles shall be posted and delivered at such times and in such manner as the Director General may, by order, from time to time appoint | 
