Iowa Code § 468.15
The notice provided in section 468.14 shall be served by publication as provided in section 331.305 before the hearing except that the notice shall be published at least twenty days before the hearing date. Proof of the service shall be made by affidavit of the publisher. Copy of the notice shall also be sent by ordinary mail to each person and to the clerk or recorder of each city named in the notice at that person's last known mailing address unless there is on file an affidavit of the auditor, or of a person designated by the board to make the necessary investigation, stating that no mailing address is known and that diligent inquiry has been made to ascertain it. The copy of notice shall be mailed not less than twenty days before the day set for hearing and proof of the service shall be by affidavit of the auditor. Proofs of service required by this section shall be on file at the time the hearing begins.
Iowa Code § 468.15
87 Acts, ch 43, §14; 88 Acts, ch 1035, §1; 89 Acts, ch 126, §2
Referred to in §468.20, 468.45, 468.48, 468.65, 468.74, 468.126, 468.132, 468.134, 468.20 7, 468.265, 468.284, 468.602