If you are in the US that’s criminal, probably on several counts. I’d notify the post office. If it happened to you it could easily happen to others.
What do you want to do with that chick? They are social animals, it’s best to not try to raise it alone unless you have other chickens to eventually put it with. If you don’t want to keep it, I suggest you call your local animal control. See what they say.
It would not surprise me that someone figured they had a male and only wanted females so did this to get rid of it. I think your odds of that being a female and eventually laying eggs is less than 50-50.
In the meantime keep the chick warm enough so it’s not fluffed up and giving a plaintive peep. It might be a little hard to tell, because if it is alone it might be giving that plaintive peep because it is lonely. Give it water in a shallow bowl, a small shallow bowl so it doesn’t drown itself. In an emergency you can feed it with stuff you have there. Corn meal is excellent. It will provide enough energy and nutrition to keep it going until a better food supply can be found. One warning, do not give it anything that needs to be chewed up. Chickens don’t have teeth and rely on ricks in their gizzard to grind stuff up. That chick may not have any of those small rocks, called grit, so only feed it stuff that is already ground up.
