65 ILCS 5/9-2-26
There shall be sent by mail, post paid, to each of the persons paying the taxes during the last preceding year in which taxes were paid on the property which has been assessed for the benefits in the proceeding, directed to the address as shown in the commissioners' report, or where not so shown, then generally to the municipality in which the improvement is to be made, at least 15 days before the specified return day, a notice stating the nature of the improvement, the description of that taxpayer's property assessed therefor, the amount of the assessment, and the date when the summons in the cause will be returnable, and when objections thereto may be filed. An affidavit of one of the commissioners, or some other person showing such service, mailing, posting, and publication, shall be prima facie evidence of a compliance with all the requirements thereof, but the publication may be proved in any other manner provided by law.
65 ILCS 5/9-2-26