It depends on your post office. At my branch, I have the smaller size box, which will hold normal envelopes and very small packages. When I have a larger package arrive, they will either put it in a locker, and then leave a key to the locker in my box, or I'll get the dreaded yellow slip and have to pick it up at the counter. I prefer the locker, because like the PO Boxes you have 24 hour access to the lockers and can pick your package up whenever; unlike going to the counter to pick up your package, which can only be done during business hours. less