... nasty new spam technique ...

I got a 10+ 'returned emails' from MSN. I checked one out and apparently I am sending out spam mail for what seems to be a dubious time share scam. When I tried to check out who had sent it was impossible to track the sender. The return address for each email was different and were clearly from some email lists.

I've reported the incident to MSN - I'll let you know what they say.