How to know if the mail that you send is already been read

1. Example: I want to send an e-mail to a friend of mine (example)

example@hotmail.com

2. So now, how to know ?
Just add the word to the mailing address: "confirm.to" (without quotes)

3. So it will be:

example@hotmail.com.confirm.to

4. And send it again

And You will receive a message telling you that your friend/victim has opened the message and at what time!