CA Ins Code Section 791.16

For the purpose of this article, an insurance-support organization transacting business outside this state that has an effect on a person residing in this state shall be deemed to have appointed the commissioner to accept service of process on its behalf, provided the commissioner causes a copy of the service to be mailed immediately by registered mail, or by a mailing service offered by a third party mailing service with tracking capability that is not more expensive than registered mail, to the insurance-support organization at its last known principal place of business. The return postcard receipt or signed receipt documentation for the mailing shall be sufficient proof that the same was properly mailed by the commissioner.