Use what you were instructed by USNA to use for plebe summer. The academic year will have a different address. But plebe summer, detailers pick up and deliver mail from USNA post office en made for their whole company. Then the detailers sort and deliver. This is different than the academic year where it’s sorted and delivered to each mid by the USNA postal service.
Initially, it’s takes longer to get stuff sorted and delivered due to the huge influx of parents mailing stuff right away. So be patient and know that as the summer progresses, things even out. It takes a minute to get it all going.
As far as local post offices, it’s not a new issue to have some resistance. Same thing happened last year (resistance to mailing to the USNA provided address). That, too, will work out. When they see you each week sending a package [emoji51].
A little FYI we learned: the REGIONAL boxes are generally CHEAPER to ship, verses PRIORITY. But you have to ask them for the regional ones. Regional are based on distance and weight, whereas priority are a standard fee regardless of distance or weight. If I was sending super heavy items, I would maybe use priority. But 9/10 times, regional was cheaper. And over Plebe year it made a significant difference!
Happy mailing!!