I have quite a bit of experience with packing cookies (and other items) for international shipping, and I did a post about it several years ago. But I thought since it is the holiday season (even though I’m a little late!), I would update that post a bit.
First, if you want to send baked goods in the mail, you need to consider the recipe. Steer clear of anything extremely fragile, anything that requires refrigeration, or anything that goes stale very quickly. Regardless of how many times you write “fragile” on the box, the package will definitely be jostled in the shipping process. and even if you pay for overnight or expedited shipping, boxes can be tied up in customs for weeks, or could be waiting for your loved one’s unit or ship to be within range of a helicopter or mail vehicle.
Because of possible delays, I try to send cookies either the same day I bake them or the next morning, and aim for a day near the beginning of the week, instead of Saturday. Underbaking the cookies a tad also helps keep them softer longer. Then, I get a cheap air-tight plastic container and line it with parchment paper or a paper towel and layer some cookies on the bottom.
I top the first layer with another sheet of parchment or another paper towel, then stack more cookies on top, continuing until I have reached nearly the top of the container. I finish with a slice of plain white bread and another piece of parchment or paper towel or two, so things are pretty snug inside when I snap the lid closed. You don’t want the cookies shaking around a lot inside the container (this goes for just about anything you’re packing, actually), so you may want to put some extra paper towels or something in there to keep it all secure. The slice of bread is a new-to-me trick that helps keep the cookies soft.
Once you have the container shut, you can wrap some tape around it if you’d like, and then make sure it’s secure inside the shipping box. I generally take everything to the post office to box it up myself, so I try to remember to bring some old newspaper I can crumple up inside the box for padding.
If you’re sending the box from the U.S. to an APO or FPO address, you need to send the box from the post office, and you shouldn’t pay for overnight or expedited shipping because it doesn’t make a difference. If the box is very heavy, though, you might want to consider a flat-rate box, because they’re discounted for military shipping. But if you’re just sending a container of cookies and a letter or two, you will almost certainly save more money by sending in a regular box.
And whatever you do, don’t send cookies in a plastic bag inside an envelope — there are few things sadder than opening up an envelope full of home-baked crumbs.