Section 31A(5)(b) in The Gujarat Rents, Hotel and Lodging House Rates Control Act, 1947
(b)When an acknowledgement purporting to have been signed by the tenant or his agent is received by the competent authority or the registered article containing the summons is received back with an endorsement, purporting to have been made by a postal employee to the effect that the tenant or his agent had refused to take delivery of the registered article, the competent authority may declare that there has been a valid service of summons.