N.Y. New York City Civil Court Law § 1908-a

§ 1908-a. Disbursement where service of process by mail is not\nacknowledged. In any action where service of process is made by mail\npursuant to CPLR 312-a, and where the signed acknowledgement of receipt\nis not returned within thirty (30) days after receipt of the documents\nmailed pursuant to that section, the reasonable expense of serving\nprocess by an alternative method shall be taxed by the court as a\ndisbursement, payable to the party serving process, if that party is\nawarded costs in the action or proceeding.\n