N.Y. Uniform City Court Act Law § 1908-a

§ 1908-a. Disbursement where service of process by mail is not\n acknowledged.\n In any action where service of process is made by mail pursuant to\nCPLR 312-a, and where the signed acknowledgement of receipt is not\nreturned within thirty (30) days after receipt of the documents mailed\npursuant to that section, the reasonable expense of serving process by\nan alternative method shall be taxed by the court as a disbursement,\npayable to the party serving process, if that party is awarded costs in\nthe action or proceeding.\n