Written or printed copies of the notice of the time appointed for the probate of the will, must be addressed to the heirs, legatees and devisees of the testator, at their places of residence, if known to the petitioner, and deposited in the post office, with the postage thereon prepaid by the petitioner, at least ten (10) days before the hearing; the notice must be issued by the judge over the seal of the court. Proof of the mailing of the notice must be made at the hearing; the same notice and proof of service thereof on the person named as executor must be made if he be not the petitioner; also on any person named as coexecutor, not petitioning, if his place of residence be known.