It doesn't. If you mark it as Spam through most email programs, it's reported to the sender (Mandrill in our case) and Mandrill automatically black-lists your email address so we don't continue to send to someone that doesn't want the emails.
Still an annoying and anti-consumer practice. Another "growth marketing" tactic that doesn't take into account the number of people who never visit that site again because of the spammy stuff.
The overwhelming majority of folks aren't so principled as to black-ball a website they like, selling products they like, from brands they like, and prices they like all because they received a cart reminder email with a special coupon inside.
Maybe you are? Just don't project that onto everyone else.
That's a win-win.