ORDERED that the order is affirmed insofar as appealed from, with costs.
The Supreme Court properly determined that the plaintiff's notice to admit sought an admission which went to the heart of the matter at issue, i.e., constructive notice of a defect, and was thus improper (see, DeSilva v. Rosenberg, 236 A.D.2d 508 ; Ashkenazi v. City of New York, 239 A.D.2d 186, 187 ; National Union Fire Ins. Co. of Pittsburgh, PA v. Allen, 232 A.D.2d 80, 85 ).
In any event, the City of New York properly responded to the notice to admit by denying receipt of the letter at issue, and by providing the reasons for its denial. Should the plaintiff prove at trial the City's receipt of the letter, she can then seek the appropriate relief at that time (see, CPLR 3123[c]). Contrary to the plaintiff's claims, CPLR 3123 is self-executing, and the penalties embodied in CPLR 3126 do not apply (see, Matter of T./P. Children, 165 Misc.2d 333, 334 ; Spawton v. James E. Strates Shows, 75 Misc.2d 813, 815 ).
SANTUCCI, J.P., ALTMAN, FRIEDMANN, and H. MILLER, JJ., concur.