Not Notice to Mortgagor

When the mortgage is executed as security for money due, or to become due, on a promissory note, bond, or other instrument, designated in the mortgage, the record of the assignment of the mortgage is not, of itself, notice to a mortgagor, his heirs or personal representatives, so as to invalidate any payment made by them, or any of them, to the person holding such note, bond, or other instrument.