California Code, Streets and Highways Code - SHC § 6505.2

(a) Not less than 45 days nor more than 60 days prior to the date of sale, the treasurer shall send notice by registered mail to the last known mailing address, if available, of parties of interest, as defined in Section 6505.4.  The content of the notice shall include the date, time, and place of the proposed sale, the amount required to redeem prior to the time of sale, and information regarding the rights of persons to claim surplus money, as defined in Section 6501.1, if the property is sold and surplus money results from the sale.

(b) The treasurer shall make a reasonable effort to obtain the name and last known mailing address of parties of interest.

(c) The validity of any sale under this chapter is not affected if the treasurer's reasonable effort fails to disclose the name and last known mailing address of parties of interest or if a party of interest does not receive the mailed notice.