Yes read it right! Spam becomes a lot worse when you try to unsubscribe from advertisement mails, because the spammers then get to know your email address is real.
If you want to become a big spammer you will need email addresses: millions of them. In order to get them at the lowest cost, spammers use various techniques which automatically search the net for addresses, or use brute force and dictionary attacks to guess typical mail address. Such as strings with common first and last names.
How spammer gets to know about email is active or not?
In order to check the addresses it has found, the spammer uses a peculiarity of the email protocol SMTP, which always answers wrongly with an error message. If there is no error message, the address is known to exist. However to find out if his mails are also being read, the spammer must provoke you to react. Therefore, many messages have fake ‘Remove’ or ‘Unsubscribe’ links which only register the fact that you opened the mail, which means you have seen the spam ad mail.
How you get more spam?
If the spammer has verified your address once, he can start making money from it because he knows you are a potential buyer. Not only does he then send you more spam than before, but also sells your data to other spammers and cycle goes on.
Of the 107 trillion emails sent in 2010, 89%were spam. That means 95 trillion spam mails every year or 262 billion every day.
Note: Don’t click on ‘Remove from list’ or ‘Unsubscribe’ link, just hit the spam button.