The trustee may make sale of any real estate or interest therein belonging to the trust estate, at public outcry to the highest bidder, after giving notice thereof by publication once a week for three successive weeks in a newspaper published in the county where the real estate is situated, or, if there be no such paper, by posting notice at the courthouse door for the same length of time; and of such sale the trustee must also give notice by mail, postage prepaid, to each creditor, in time to reach him 10 days before the day of sale. But nothing contained in this section shall prevent the assignee from exercising the powers of sale or other powers conferred by the deed of assignment, unless specially restrained from so doing by an order made in writing by the circuit judge and filed in the court.