Not to deliver it, but to take the package or envelope, check the address, then put it in a pile to go to a distribution center in the appropriate, proximal zip code of its destination. That done, the mail might wait up to a day to be flown out, two days at times, then another day to be delivered by ground.
Some breeds of dogs have a natural curl or bend to their tails. But others have been selectively bred to take this curl to an extreme, cork-screw shape. Dog breeds with curly tails referred to as screw tails include Boston Terriers, Pugs, Bulldogs and French Bulldogs.
The flap-down ears and famous curved tail of the dachshund have deliberately been bred into the dog. In the case of the ears, this is to keep grass seeds, dirt, and other matter from entering the ear canal.