Have you ever tried to do unsubscribe in junk mail or Spam? If you haven't tried it, you'd better never do it. If you open spam emails you will notice that they also contain a link to delete your email from the list.
Don't think it's nice because it's not. The spammers didn't add the deletion link because they thought it might bother you. Nor did they realize that some people will never respond, so they try to narrow down their lists for more efficiency. 
Clicking "Unsubscribe" or Unsubscribe in a spam email will make a very big mistake. The results will be completely opposite to what you expect.
Let's see why:
While "legitimate companies" appear to respect each recipient's deletion requests, malicious users they use the unsubscribe links to confirm your address and send you more spam.
Sophos Alan Zeichick reports that a click on the unsubscribe tells the sender that you opened your email, probably because you were interested or why you might have imagined that the spam was real.
By visiting the fake deletion page that the spammer has created, you are giving him information about your browser, operating system, and address your IP, risking even more and more targeted malware attacks.
If an email looks like an unwanted message, do not click on any link. Simply mark it as spam and immediately send it to your spam folder.
