Ohio Rev. Code § 5309.16
The answer day of the notice set forth in section 5309.15 of the Revised Code shall be the third Saturday after the publication is completed. The probate court or the court of common pleas shall within seven days after the first publication of said notice in a newspaper, cause a copy of such published notice to be served on the defendants by registered letter, mailed by the clerk of the probate court or the clerk of the court of common pleas, with a five day return card thereon, to every defendant named in said notice whose address is given or known.
The court shall cause a copy of the notice attested by the clerk to be posted by the sheriff in a conspicuous place on each parcel of land included in the application, at least fourteen days before the answer day of such notice. Such sheriff's return shall be proof of such posting. The court may cause additional notice of the application to be given or additional persons to be made parties and served as provided by law in civil actions. The court shall, so far as it considers it possible, require proof of actual notice to all adjoining owners and to all persons resident of the state who appear to be in possession or occupancy of, or to have any interest in or claim to, or lien or charge upon the land, or any part thereof, included in the application. If any registered letter containing such published notice, mailed by the clerk to a defendant named as a resident of the state, is returned undelivered, such notice shall be remailed by the clerk to any other address of such party of which the plaintiff is able to learn and which he shall designate by amendment of his application filed in the case. If there is no other address, or if said letter is again returned undelivered, the clerk shall thereupon, on the praecipe of the plaintiff, issue summons for such defendant as in other cases. Such summons shall be directed to the sheriff of each of the counties in which the plaintiff, in his application or any amendment thereof, states that such defendant resides. Such summons shall have attached thereto an attested copy of said published notice. If said summons and notice are returned unserved because the defendant cannot be found, then such defendant may be regarded as having been served by such published notice as a person whose place of residence and post-office address are unknown. In all cases, whether of original registration or subsequently arising in any way in reference to registered land or any interest in or lien or charge upon it, in which notice is required or may be ordered by the court to be given to parties by the clerk by publishing or mailing, or both, the certificate of the clerk, stating that he has served the notices as required or as directed by the court and stating which of the letters mailed by him containing said notices have been returned to him undelivered, shall be filed in the case before any order or decree is taken or made and shall be proof of such service.
R.C. §5309.16