Homeless the dog from Cutting Edge Engineering Australia (Youtube) is a Doomguy for incoming mail – and toys. Rip and tear, rip and tear.
Puppies sometimes chew on our favourite shoes, exactly because they like the smell. Some dogs have a protective instinct that a foreign smell might trigger when they're alone, leading to e.g. mail being chewed, especially when young, impulsive, bored, and not a thought stirring in their little noggin.