GMAIL uses the email addy and header to advertise to you. I see that all the time. It is at the top and I don't even see it anymore since I know to ignore it.
Comcast is worse. My mother wondered why she was getting ads at the portal so I told her. She wasn't happy. She called Comcast and nicely told them about it. She said she doesn't see them anymore. So, Comcast does have an opt-out. I was there a month ago and didn't see them.
