Cal. Welf. & Inst. Code § 14124.3

Notice of any act of the department required by law or department regulation to be given may be signed and given by the director or an authorized employee of the department and may be made personally or by mail. If made by mail, service shall be made in the manner prescribed by Section 1013 of the Code of Civil Procedure. In the case of service by mail, the service is complete at the time of deposit in the United States Post Office.