The servee has to be a current resident of the service address. For service methods aside from personal service, like substitute service or postings, confirming the servee's residency is a necessary component in ensuring that service is legally compliant. This confirmation is entirely your responsibility unless explicitly stated otherwise in the Special Handling notes. Confirmation of residency is determined through conversation with a co-resident, neighbor, or leasing office personnel. The best process servers ask for the servee by full name coupled with a direct question like, "Does Jeff Mann live here with you?" If the answer is yes, then do what makes sense for your state in that situation - either make an attempt adding "subject resides but not available at this time," or perform substitute service if the circumstances allow.
Sometimes people will lie about who they know, where someone lives, or whether they can accept service documents. In these cases, the special handling notes are there to help. When you are expected to serve documents regardless of what the person at the door says (e.g. "No Jeff Mann does not live here. He moved away"), then the special handling notes will very explicitly state these expectations. Oftentimes, the phrase "serve regardless" is used.
We have a skip-trace team, staffed by licensed private investigators. They are always striving to determine the best address for service. Sometimes you will find yourself asked to make further service attempts at a residence that you had previously marked as a Bad Address, with information contained in the special handling notes. If you receive special handling notes from our investigations team, it is meant only to be treated as supporting evidence to assist you in the service. It is not intended to be taken as confirmation of residency.