Thanks for this info, Stu. Can I also add that typically this scammer ALSO asks in the swap that you DON'T send it with confirmation or signature confirmation? This would require him to sign for it, which would implicate him obviously in mail fraud.
Instead, he'll ask you, "Please don't send with signature confirmation. I'm at work during the day and so won't be able to pick it up. The mailman will leave it at my house, so I don't need the confirmation."
Be careful! He's very tricky and sounds very interested... but he's just trying to steal from you! Be wary if a swapper asks you to send it without any confirmation/proof or keeps asking you if you've "sent the package yet" while he doesn't provide any evidence that he's sent your end.