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If the papers are a "summons and complaint," i.e., a document stating something like "Notice: you are being sued...," then you must be served personally. The exception is where the person serving the papers knows that you are in the house and has spoken with you, and you are intentionally refusing to open the door to accept the papers -- then the process server can drop them on the door step and announce it to you.
Note, that even if you haven't been properly served, the plaintiff may state that you were, and get a default judgment against you -- at which point you would have to ask the court to set aside the judgment so that you could defend. The point is that unless you have some good reason for avoiding service temporarily, you will eventually have to defend, so it may be in your nterest to just treat the documents as if they were properly served and answer the complaint.
That said, if the papers are not a "summons and complaint," then it doesn't matter how they are served. If you have them, then you are on legal notice of their contents.
What is the title of the document on the top page? What does it say?
If the document has a court stamp stating the filing date, then it's an actual lawsuit. If there is no stamp, then it could be a trick to make you think you're being sued. If you want to know for sure, call the county courthouse and give the clerk the case number XXXXX ask them to confirm that it's been filed.