The order must direct the publication to be made in a newspaper to be designated as most likely to give notice to the person to be served, at least once a week for four (4) consecutive weeks.
In case publication is ordered where the residence of a nonresident or absent defendant is known, the order must direct a copy of the summons and complaint to be deposited within ten (10) days in any post office, directed to the person to be served at his last known post office address. When publication is ordered and made, the service of summons is complete at the expiration of the period of publication. When personal service of summons is ordered and made outside of the state, the service is complete at the time of service.
Idaho Code § 5-509