Legal Question in Credit and Debt Law in California

I would recommend sending it both by certified mail-return receipt, and by first class U.S. mail. In that way, if the person refuses to sign for the return receipt letter, at least the first class letter will have been mailed as well. Keep copies of the envelopes and letter. If you can use metered mail, it will show the date sent. As you've discovered, the law does not specify what method to use. By the way, the court's website will help you to prepare the demand letter: http://www.courts.ca.gov/11145.htm .