Unless otherwise required by law, service of the following documents shall be made by personal delivery or by mail: Notices of the hearing; Default orders; Prehearing orders; Final decisions; and Exceptions to proposed decisions and appeals of final decisions. Service upon a party to whom a permit, certification, or license has been issued by the Commission or Secretary may be made by delivering a copy to the most recent address provided by that party to the Commission or Secretary. Proof of Service. The person serving a document shall certify: To whom the document was sent or delivered; The address to which the copy was sent or delivered; The date the copy was sent or delivered; The manner of service; and The name of the person who sent or delivered the document.