Besides Deb's excellent suggestion of using shredded paper to pack your Zip-lock bags of cookies, I have also found that packing the zip-locked cookies in a box and then packing that box within a second box helps. I often use bubble wrap to cushion. About a million years ago I made and shipped 720 cookies to my sister (going from southern Indiana to northern Ohio), and not a single one was broken by UPS-ing a box within a box. As I recall Mother and I made 8 different kinds for a high school youth orchestra's members to enjoy during a practice session.