"**w when a sender includes an Unsubscribe Link in a Promotions, Social or Forums message, Gmail will surface it to the top, right next to the sender address. If you're interested in the message;s content, it won't get in the way, and if **t, it'll make it easier to keep your inbox clutter-free. Making the Unsubscribe option easy to find is a win for everyone. For email senders, their mail is less likely to be marked as spam and for you, you can **w say goodbye to sifting through an entire message for that one pesky link," informs Google.
The Unsubscribe Link has already been used for Google+ messages. When you click it, Google shows this message: "Google+ provides a page at plus.google.com where you can manage your email subscriptions." Google links to a page that lets you Unsubscribe from certain Google+ email **tifications, like the ones sent when someone shares or comments on your content.