Ordered that the order is affirmed, with costs.
The plaintiffs served process only by mail pursuant to CPLR 312-a. The defendant did not return the acknowledgement. "The mailing of process pursuant to CPLR 312-a does not effect personal service * * * If the acknowledgment of receipt is not mailed or returned to the sender, the sender is required to effect personal service in another manner" (Matter of Shenko Elec. v. Hartnett, 161 A.D.2d 1212, 1213; see also, Nagy v. Heuss House Drop in Shelter for the Homeless, 198 A.D.2d 115; Patterson v. Balaquiot, 188 A.D.2d 275). Since the plaintiffs did not attempt another manner of service, the service was defective. Accordingly, the Supreme Court properly dismissed the complaint. Thompson, J.P., Rosenblatt, Ritter, Friedmann and Krausman, JJ., concur.