California Code, Code of Civil Procedure - CCP § 751.10

If the affidavit discloses the name of any person claiming any interest in or lien upon the property adverse to the plaintiff, a copy of the summons and complaint and affidavit shall also be served upon such person, if he can be found, in the manner provided by law for the service of a summons in a civil action, other than by publication. Service shall be made during the period of the publication of the summons. A copy of the memorandum provided for in Section 751.07 shall be appended to the copy of the summons served upon any such person.

If such person cannot, with reasonable diligence, be served as provided above within the period of publication of the summons, a copy of the summons, memorandum, complaint, and affidavit shall be mailed, postage prepaid, addressed to him at the address given in the affidavit, or, if no address is given, at his last address known to the plaintiff, or, if none, at the county seat of the county in which the action is brought, forthwith upon the expiration of the period of publication.