The Illinois Certificate of Mailing Citation is a document issued by the Illinois Secretary of State that serves as proof of mailing an official document. It is not necessary for a Certificate of Mailing Citation to be filed with the document itself. There are two types of Illinois Certificate of Mailing Citation: Certificate of Mailing Citation for Service of Process, and Certificate of Mailing Citation for Notice of Filing. The Certificate of Mailing Citation for Service of Process is used to provide proof of mailing a summons and complaint to a defendant that is being served with legal process. The Certificate of Mailing Citation for Notice of Filing is used to provide proof of mailing notice of the filing of a document, such as a motion, to a party, other than the defendant, who is affected by the document. The Certificate of Mailing Citation will include information such as the date the document was mailed, the address of the recipient, and the name of the sender.