Legal Question in Real Estate Law in California

It depends on the terms of the rental agreement. A good rental agreement has a clause that specifies how notices are to be given and when they are deemed received. In the absence of such a clause it becomes a question of "reasonable" and "actual" notice. If you want to avoid a fight over whether notice was given and when it takes effect, the only sure-fire option is hand delivery or physically posting it on the door of the property. Anything less than that and you give the tenant a chance to dispute it. Next best thing is something like a FedEx letter. I don't use certified mail unless required, because the recipient can refuse to pick it up or sign for it. Also, though it does not specifically apply to landlord/tenant notices, many notice periods are extended by five days if mailed, and two days if sent by FedEx or other overnight service. So if you want the most confirmed notice in the shortest time, without hand delivery, I recommend an overnight service letter and two extra days.