Spam on new UNUSED Cox email account

A while back I was fed up with the amount of spam I was getting so I got a site to host my email with my own domain.  That way I could control my email account directly and could get my ISP connection from anyone and not have to move all my online stuff to a new email account.  I WAS getting HUNDREDS of spams a day. After the switch it immediately cut out ALL the spam and it has stayed good for months and months now.

So a few weeks ago I dropped ATT DSL and went to Cox for my internet connection.  Part of it was a new Cox email address which I went ahead and set up and never used for anything but send a test message to my main non Cox account with it.  I NEVER gave it out online although it IS used by this forum.

So my question is this.  Why am I now receiving SPAM on this new Cox email account?  How is this email address being disseminated if it's no my me?  Is Cox selling the email lists or "sharing" it with other organizations?

While It's nowhere as bad as it was with ATT DSL it is starting to pop up almost daily.

Is there an OPT OUT somewhere that I can join?