I'm lucky in that I didn't have any
Having had a look down old email messages I suspect there is some inkling of what might have happened
All the emails I have had have come from an email address made up of a mixture of letters and numbers, these always seem to be a block of 8 digits-4 digits - 4 digits - 4 digits - 12 digits @ the usual.com
If each user has his own string rather than being a unique code per conversion then it might be possible someone has either used a random generator and hit used addresses or has discovered a list of these addresses somewhere - however the user ID seems to change occasionally
The question is where would you find the list of codes to email someone, the answer is simple - log onto anyones profile and right click the "message xyz" code and copy the link - this has that mixed ID code as part of the link
I have tried to email myself using the code from here and it hasn't worked but that might be due to it being turned off
It's sounds more likely it was some bored teenager who built some sort of Web crawler to harvest them for a laugh to me than anything majorly malicious
