I receive an email about once a month that promises to do something neat or give me a gift certificate if I forward it to some number of friends. Hating junk mail and chain letters as much as anyone, I refuse to forward.
There are no attachments to the messages. How do they work if they do? If they don’t, why are they created?
They don’t work; it’s a scam.
There is no possible way to track email in the manner that these letters claim. There are lots of letters making the rounds that use this trick to get people to forward them to all their friends. Thus, the guy who started the chain letter can claim that he’s, like, really clever.
I believe you will find a lot of information about this at http://www.snopes.com