Do I have to take an item to the Postal Office open or close?

I have to ship my first item with USPS, but I'm not sure if they check the box or if I have to seal the box before I send it.
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You take the item to the post office closed. If going international, don't forget the customs form. It is also a good idea to put your name and address inside the box in case the outer label comes off in the automated equipment. The postal service does not employ scanners to scan "through" the box. We use equipment to detect bio hazards in letters, but parcels are visually screened.
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Jsut close the box and declare the item. Don't worry about the verification as they have their own scanner to scan through your box.