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As of now Gmail does not support 'blocking' emails. However, one can set up emails from specific email-ids to be sent directly into the 'Spam' folder.
There are Chrome and Mozilla extensions available which notify you whether the mail that you sent has been opened or not. You can track your mails through them and know if they are being read or sent to spam.
You cannot block emails on Gmail. You can however put the email address on the spam list so any email with this particular email address will go directly to the spam folder. Or you can create rules to delete emails with this email address as soon as you get it.
In both occasion the owner of the email address won't know about these.
