In California the courts hold that where the process server's actions were calculated to, and did, result in actual notice, it meets the reasonable diligence requirement. Afterwards, a copy of the summons and complaint must be mailed by first-class mail, postage prepaid, to the defendant at the place where the copy of the summons and complaint were left. Service is complete on the 10th day after mailing. In cases where the defendant is a willing participant, the entire service of process ordeal can be made effective by simply mailing the defendant a Notice and Acknowledgment of Receipt. If the summons is Notice is not returned in 20 days, the defendant is also liable for the costs incurred in serving the defendant.
Most jurisdictions have a standard form that can be filled out and signed.
Such a defendant might have departed from California, or he or she might be concealing him or her self to avoid service. The newspaper in which publication is to be made should be named in the order and should be designated as most likely to give notice to the person to be served. The Government Code requires publication once a week for four successive weeks, in a newspaper published once a week or more often, with at least five days intervening between the respective publication dates, not counting such publication dates. The court may order a longer period of publication, and the service is complete at the expiration of the time prescribed by the order for publication. The order for publication must direct that a copy of the summons and complaint be mailed to the defendant if his or her address is ascertained before the expiration of the time prescribed for publication of summons.