In a proceeding in effect to stay arbitration, the appeal is from an order of the Supreme Court, Nassau County, dated November 9, 1977, which (1) granted the petitioner’s motion to reargue a prior order of the same court and (2) upon reargument, denied appellant’s motion to dismiss the demand for arbitration. Order affirmed, with $50 costs and disbursements. Although the demand for arbitration, which was served by ordinary mail, did not satisfy the requirements of CPLR 7503 (subd [c]) (see Jefferson v Government Employees Ins. Co., 48 AD2d 855), the appellant has waived its objection by generally appearing in the arbitration proceeding in that it (1) requested a change of venue and an extension of its time to answer in a letter to the American Arbitration Association; (2) participated in the selection of the arbitrators and the scheduling of the arbitration hearing; and (3) submitted an application to Special Term, which had the effect of adjourning the arbitration hearing. The appellant’s active involvement as a genuine actor in the proceeding antedated its objection to the improper manner of serving the demand. Consequently, the objection has been waived (cf. CPLR 320, subd [a]). Suozzi, J. P., Cohalan, Margett and Hawkins, JJ., concur.