Whenever the department is authorized or required to give any notice under this chapter or other law regulating the operation of vehicles, unless a different method of giving such notice is otherwise expressly prescribed, such notice shall be given either by personal delivery thereof to the person to be so notified or by deposit in the United States mail of such notice in an envelope with postage prepaid, addressed to such person at his address as shown by the records of the department. The giving of notice by mail is complete upon the expiration of four days after such deposit of said notice. Proof of the giving of notice in either such manner may be made by the certificate of any officer or employee of the department or affidavit of any person over eighteen years of age, naming the person to whom such notice was given and specifying the time, place, and manner of the giving thereof.