Whenever in the Communicable Disease Prevention and Control Act (Section 27), service or notice of any order or demand is provided for, it shall be sufficient to do so by registered or certified mail if a receipt therefor signed by the person to be served or notified is obtained. The receipt shall be prima facie evidence of the service or notice in any civil or criminal action.
Source:
Section 120105, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=HSC§ionNum=120105..