Eric - I get a lot of discs delivered by mail w mostly good results. Our condo is 15 units w similar box to you and only one of the parcel boxes can accommodate LP, every now and then the key goes to wrong box...they normally get to me because I feed the building now and then... that’s my theory anyway
I think it is on the shipper to provide insurance and make the claim w USPS. They lost a Benz Rosewood I shipped to a buyer, the claim process a royal hassle - let seller resolve.
hope this finds ya well !!!!!
jim