I do this too. I currently have about 25 email addresses killed because of all the ass40L3 companies that sold the addresses. This would include nfl.com, mlb.com, many more. I do it exactly like you say.
The spam tips off who sold it, at which time I begin forwarding that entire email address to the CEO of the company that sold it, or the support email address.--
"Free your mind and your behind will follow" - The iBrotha