When I visit certain websites, namely stores, without signing in, nor providing them with my e-mail address, I receive, shortly after, an e-mail offer from them, with the very product I was looking at. It's one thing to see banners all over the web related to your browsing habits, but I find this kind of marketing quite invasive. How do I keep this from happening? All my Tracking and General Security boxes are checked on my Firefox preferences, so I don't know what else I could do to ensure my privacy.