What similarities are there in the purchases that go missing?
Are they all from one country?
What kind of mailbox do you have? Community? End of driveway? By door? In door? Apartment house?
If they are consistently from one country, then the problem is there.
There is a scam mostly from China, where inexpensive items are just never shipped.
Since some customers will forget their low cost order after a month has passed and others won't know how to open a Dispute, the seller keeps the money for doing nothing.
And if the buyer does go to resolution, an offer of a replacement, which also never arrives, will fob off quite a few until the dispute deadline passes.
It's not that Chinese sellers are less honest than any other, but there are a heck of a lot of them. Just as there are a heck of a lot of US buyers and sellers report more problems with them than with other nationalities.
Then there is 'porch theft' which is basically people stealing parcels after delivery. We might include theft by contract workers during the holiday period here.
And lowest would be employee theft before delivery, because it wouldn't take too many reports to put a postmaster on notice that something was up on a given postal walk.
