Section 65. Any mortgagee doing business in the commonwealth who makes in excess of five mortgage loans per year shall accept a written memorandum of a preliminary contract of insurance pursuant to section ninety-eight of chapter one hundred and seventy-five as evidence of insurance from any duly licensed agent, broker or insurance company; provided, however, that a contract for insurance for a term of not less than one year is issued within thirty days of said memorandum, or in the event of the cancellation of said memorandum, the mortgagee shall be provided with prior written notification thereof.