Illinois Proof of Mailing and Publication is a set of methods used to provide legal proof of the mailing and publication of a document in the State of Illinois. This proof is usually required for legal documents such as summons, notices, complaints, and other court documents. There are two types of Illinois Proof of Mailing and Publication: Proof of Mailing by Registered or Certified Mail and Proof of Publication by Newspaper. Proof of Mailing by Registered or Certified Mail is a method of providing proof that a document was sent to an individual or entity via registered or certified mail. This method involves obtaining a postmarked receipt from the U.S. Postal Service showing the delivery address and the date the document was sent. Proof of Publication by Newspaper is a method of providing proof that a document was published in a newspaper. This method involves obtaining an affidavit from the newspaper showing the date and location of publication. The affidavit must be signed by the newspaper’s publisher, or by someone authorized to sign on behalf of the publisher.