Unsubscribing doesn't seem to work for Groupon, Facebook, Twitter (I never signed up!), etc.
I select the UNSUBSCRIBE and they pop back saying "We're sorry! Is it something we did. Don't Go!"
And then I STILL continue to get emails.
For those pesky organizations, I create a dummy email in gmail and then update my Profile email address.
Since they chose to ignore my request for no more email, they can fill up a dead drop.