Ok guys cut the jokes Andy does have a valid point.
When you sign up for anything online now-a-days there is always a confidentiality claus which you tick if you don't mind them sharing your addy, same with paper contracts.
Simple reason for this is that a lot of these places (at one time) once they had your details would simply start selling them to all and sundry.
If as Andy suggests that the addy used has a certain level of security then it is possible that a dealer may be farming out details for a few extra bucks, only way we will know is to see if more turn up.
Ken
A word of warning the letters look very much to me as the typlical Chinese Uni student scam, this is where a couple of savy students go to lengths of even building very impressive websites and mail out's (Email mostly) but all they ever do is take the money and never send out, when the heat gets to much that scrap the site and start another.