I usually send tiger butter (chocolate-peanut butter fudge) to my relatives. It's not a true fudge- I use marshmallows and crisped rice as a stabilizer. They are soft, but not melty. I find they hold up fantastically, and my family looks forward to getting their packages.
I agree with tenthz, use Pringles cans for standard size cookies. I've used Pringles canisters to ship mini pizzelle cookies, and they are very delicate. I just put a piece of wax paper or parchment paper in between each one.

Agree with luvcookbooks. Bar cookies work well. Any kind of cookie but the most delicate holds up well for shipping. I ship about 5000 cookies during the christmas holiday season all over the world...one trick I use for long hauls is to freeze the cookies. I do omit the fancier wrap for war zones. But wrap them tight in wax paper; think of doing it like a jacob's ladder. Then wrap the stack in more wax paper. Then put the bundle in a ziplock and stick it in the freezer overnight. I then take that bundle and use a sturdy box with lots of cushioning.

By freezing, it makes them more sturdy and buys them a few more days of freshness for very long postal trips.

Good luck.

No recipes here, but if you save the containers from Pringles (or anything similar) they are great for packing! Chocolate chip cookies fare well shipped like this. You can even just wrap the can in brown paper and slap a shipping label on it.

Biscotti are my stand-by care package cookies. Even sent them to my bro-in-law in Afghanistan and they survived intact, mostly.

The Field Guide to Christmas Cookies rates cookies for sturdiness. Also older Betty Crockers and the out of print Virginia Pasley's Christmas Cookie Book.
I send cookies to my mother in law. Gingerbread, sugar cookies, and even cinnamon stars (a fragile rolled cookie with meringue topping) mail well, frosting, sprinkles, and all. I pack them in plastic or cardboard boxes with wax paper between the layers. I use popcorn, popped, (no butter or salt, natch) as a substitute for styrofoam packing peanuts. Bar cookies like brownies would also mail well. They can be wrapped individually in plastic wrap or wax paper. The little wax paper packages can be tied with raffia.