Section 21(3) in The Company Law Board Regulations, 1991
(3)Save as otherwise provided in sub-regulation (2), notices and other documents, which are required to be served on any person, other than a company, shall be served by delivering or tendering a copy thereof to such person or his authorized representative, where he appears by such representative or by prepaid registered post, acknowledgement due, addressed to the last-known address of such person.
