California Code, Public Utilities Code - PUC § 29221

At the same time, the chief financial officer shall deposit in the post office a copy of the notice, enclosed in a sealed envelope, postage prepaid, addressed to the registered owner of any such bond, note, or other evidence of indebtedness, registered pursuant to this part, whose address appears upon the record in the chief financial officer's office.  If the bond, note, or other evidence of indebtedness is not presented within the time specified in the notice, the interest upon it ceases and the amount due shall be set aside for the payment when presented.