Section 39B. In an action against the subscribers of a reciprocal or inter-insurance exchange defined in section ninety-four A of chapter one hundred and seventy-five and authorized to transact business in the commonwealth under said chapter, service may be made upon the attorney in fact of such subscribers, as defined in said section ninety-four A, if a domestic exchange, as so defined, instead of on the commissioner of insurance under clause Third of section one hundred and fifty-one of said chapter one hundred and seventy-five.