When service is made under Code of Civil Procedure section 1011(b) and a party's residence address is unknown, the notice or papers delivered to the clerk, or to the judge if there is no clerk, must be enclosed in an envelope addressed to the party in care of the clerk or the judge.
The back of the envelope delivered under (a) must bear the following information:
"Service is being made under Code of Civil Procedure section 1011(b) on a party whose residence address is unknown."
[Name of party whose residence address is unknown]
[Case name and number]
Cal. R. Ct. 3.252