If it's junk mail, chances are that the sender is using a different
address every time it's sent. That's why blocked sender lists are so
ineffective in combatting junk mail.
--
Brian Tillman

Actually the case is one of testing the feature. So, once I tried blocking
myself and sending an email from my account, and second time I tried
blocking one of my friend's ID and sending mail from his account. Both were
downloaded to my inbox.