(a) All process issued by the commission shall extend to all parts of the state, and any such process, together with the service of all notices issued by the commission, as well as copies of complaints, rules, and orders of the commission, may be served by any person authorized to serve process issued out of courts of law, or by mail, as the commission may direct.
(b) In instances in which service is had by mail, a duplicate of the instrument served shall be enclosed, upon which duplicate the person served shall endorse the date of his or her receipt of the original and promptly return the duplicate to the commission.
(c) Any person who fails, neglects, or refuses to promptly return the receipt and duplicate shall be guilty of a Class A misdemeanor.