N.J. Stat. § 40:37-229
No mortgagee whose mortgage shall have been recorded or registered before the sale, shall be divested of his rights in and to the real estate unless, after written notice shall have been given to him by the purchaser for a period of six months, he shall neglect to redeem the real estate by paying the amount actually paid by the purchaser, including taxes and assessments subsequently made, together with interest at the rate of six per cent from the date of payment and all costs or charges which the purchaser may have been by law obliged to pay. Notice to every mortgagee who is a resident of the county shall be served personally. If he is not a resident it shall be addressed to him by mail at his place of residence as stated in the mortgage or any assignment thereof.
Any mortgagee who shall redeem the property as hereinbefore provided may collect the amount paid as a part of the debt due, and shall be entitled to receive and hold by assignment the declaration of sale, as evidence of such payment and as further security for the repayment of the sum so paid, with interest.
N.J.S. § 40:37-229