(735 ILCS 5/2-206) (from Ch. 110, par. 2-206)
    Sec. 2-206. Service by publication; affidavit; mailing; certificate.
    (a) Whenever, in any action affecting property or status within the jurisdiction of the court, including an action to obtain the specific performance, reformation, or rescission of a contract for the conveyance of land, plaintiff or his or her attorney shall file, at the office of the clerk of the court in which the action is pending, an affidavit showing that the defendant resides or has gone out of this State, or on due inquiry cannot be found, or is concealed within this State, so that process cannot be served upon him or her, and stating the place of residence of the defendant, if known, or that upon diligent inquiry his or her place of residence cannot be ascertained, the clerk shall cause publication to be made in some newspaper published in the county in which the action is pending. If there is no newspaper published in that county, then the publication shall be in a newspaper published in an adjoining county in this State, having a circulation in the county in which action is pending. The publication shall contain notice of the pendency of the action, the title of the court, the title of the case, showing the names of the first named plaintiff and the first named defendant, the number of the case, the names of the parties to be served by publication, and the date on or after which default may be entered against such party. The clerk shall also, within 10 days of the first publication of the notice, send a copy thereof by mail, addressed to each defendant whose place of residence is stated in such affidavit. The certificate of the clerk that he or she has sent the copy in pursuance of this Section is evidence that he or she has done so.
    (b) In any action brought by a unit of local government to cause the demolition, repair, or enclosure of a dangerous and unsafe or uncompleted or abandoned building, notice by publication under this Section may be commenced during the time during which attempts are made to locate the defendant for personal service. In that case, the unit of local government shall file with the clerk an affidavit stating that the action meets the requirements of this subsection and that all required attempts are being made to locate the defendant. Upon the filing of the affidavit, the clerk shall cause publication to be made under this Section. Upon completing the attempts to locate the defendant required by this Section, the municipality shall file with the clerk an affidavit meeting the requirements of subsection (a). Service under this subsection shall not be deemed to have been made until the affidavit is filed and service by publication in the manner prescribed in subsection (a) is completed.
(Source: P.A. 87-1276.)