An individual is served if the papers are delivered to somebody of adult age in the household that’s their last known address. The idea behind service is that it shouldn’t be a game to see if a person needs to place the papers directly into the hands of the defendant. The real question is: will the the service reasonably alert the person who is the defendant that there’s been an action or a proceeding filed against them? If the answer is yes, then the courts are going to say the person knows that they’ve been served; they know that they need to take steps to protect their legal rights.
Service can sometimes be difficult because people are trying to evade. They see the sheriff coming and don’t answer the door. That’s why attorneys may have to file affidavits from the process server that the defendant seems to be evading service. The court might then enter an order saying all the attorney needs to do is send a mailing with a certification of the mail, post the papers at the person’s last known address and that person will be deemed to be served even if the sheriff never puts the papers directly in their hands.