You should never use the unsubscribe link in an email to unsubscribe because it could confirm to spammers that your email address is active and could result in even more spam.
Anytime you receive an unwanted email you should report it as spam by clicking the "Mark as spam" icon in the toolbar. If its a newsletter, you'll receive a notification that it is a newsletter and will ask you if you'd like to "Unsubscribe" or "Report spam". If you click "Unsubscribe" you will safely be unsubscribed from the newsletter.