- See which domain it's coming from
- Google "whois <domain_name>"
- Get the registrant's email as well as the domain admin's email address
- Mail them & ask them nicely to stop, ask again. Lose your cool and start doing this : http://i.imgur.com/g9iHQGw.jpg
- Wait and see if they remove you from the mailing list
- Redirect back to them by setting up a filter on the mail server : http://i.imgur.com/eEZKSXw.jpg
- No more spam from them