Tanga does this. It's very easy to unsubscribe, but that's beside the point. I bought one thing from there and started getting "daily deal" mails, very annoying. I try the unsubscribe, but then if mail is still flowing, I will mark as spam, but I am very conservative with that Spam button. I manage mail for a large ISP and too know the horrors of customers complaining that our IP space is blacklisted.