2006 New York Code - Disbursement Where Service Of Process By Mail Is Not Acknowledged.

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