Here are tips to ensure your cookies arrive intact:
1. Store cookies in the freezer until you are ready to ship or deliver them.
2. Line each tin with foil (though it sounds redundant, it adds an extra cushion to keep cookies from shifting within the tin).
3. Pack cookies fairly tightly, layering the more substantial on the bottom.
4. Add an extra layer of foil or waxed paper across the top of the cookies, which overlaps the sides of the tin. This keeps the cookies fresher and helps hold the lid in place.
5. Place the tin in a box (with whatever other items you might be shipping), filling in the gaps around the tin with crumpled newspaper or packing material.
6. Unless you are pressing right up against the holiday, you don't need to ship overnight. They'll stay fresh on their regular delivery journey - and will probably be eaten before they have a chance to get stale anyway.