Brisco,
Maybe you know this already but I can let you in on a (couple) little secret(s).
If someone has an yahoo email account (or what ever), many times people use their names in some form or another, like an abviation of their first name; jsmith. There are programs out there that take iterations of names and send emails out in groups. For instance I have a catchall account on my servers which I get to see a lot of fantastic email - most are from "banks" asking someone on my server to send them their personal info. The server is setup to copy those emails for security reasons but also bounce all of them back to the sender so to look like they are rejected (yes there is a reason for this). So these programs use iterations of names they pull out of databases or mass opt-in mailing lists to create a base of data. What gets bounced back usually gets deleted and what doesn't gets put into the list.
The other thing are the lists, which you seem to be pointing at. When anyone opts in to say a newsletter or some other service, your email address is now their property. SO a lot of places, like say Bestbuy who you just applied for that online rebate for that new Ipad3, you have no control over what is done with that email address. Bestbuy may say they don't sell info but got to tell you that if that rebate is a third party deal, it has no control over it.
