The best cookies for mailing are ones that don't break easily, like drop cookies, refrigerator or icebox cookies, and molded cookies. Brownies and unfrosted bars are good to send, too.
To keep flavors from changing or blending with others, pack cookies in separate containers or wrap the different types separately within a container.
Use sturdy foil-lined containers or tins. Wrap round cookies back to back in pairs, stacked flat or on end. Layer bars between sheets of waxed paper. Cushion well with tissue or waxed paper up to the top of the container to keep them snug.
Place crumpled newspaper, shredded paper, packing peanuts or other packing material below, above, and between containers to cushion them in the shipping box.
Seal the box with shipping tape and cover the address label with clear tape for protection. Mark the package clearly with the word "perishable" to encourage careful handling.