This makes me sick. He knows what he's doing is wrong otherwise he wouldn't put the 40 and the thank you in as a little pat on the back type thing. If I lived around there I'd drive by and do some investigating.
Do a trade with him at the same location but I'd just send a box of tissue and then sit and eyeball the house to see who picks up the package.
Honestly, this would be my advice, however I understand that this course of action would have some pretty serious issues:
1. The person would need to be a local, and would need to be someone who was prepared to spend several hours observing this house.
2. It's 2014, and this isn't an '80's cop movie. The scumbag would almost certainly be instantly aware of someone sitting in a car where they weren't supposed to be. So, the person who was observing that spot in order to see who got the mail would almost certainly need to be doing it from a hidden position in which they couldn't be seen by this toolbox just coming down the street, stopping at the mailbox and grabbing the goods.
3. Which brings up another problem. Say it's someone that lives a few streets over. There's a chance you'd have to tail the guy to where he ACTUALLY lives, in order to get the address. You might be seen, and this guy might possibly decide to confront you. So, suddenly this goes from tailing a punk-ass thief to possibly having a self-defense situation arise. In which case, the cops won't look kindly on you, because personal property isn't worth a possibly violent personal confrontation.
So, sadly, there's a level of effort here that really puts it out of the realm of good common sense for someone who's not Jim to execute. Now, if
I had been rooked for that knife, I would have no problem doing any of the above, merely because I had a personal stake in the situation. But, if I were a local and someone else here had had this happen in my area, I have to say that no, I wouldn't expend a level of effort that could possibly see me in a face to face altercation/confrontation with the thief trying to help the nonlocal member who got scammed. There'd be no way I could justify it.