Track Sent Email In Gmail Has Been Opened Or Not

We working hard to create our email newsletter to send to our loyal fans. But how do you know. Your sent email has been opened or not.On Facebook, WhatsApp, when we send message then we immediately know that our seen message has been opened. But this is not in the case of email. After sending Email to our client through email, we have to wait until we get an reply message from that client.Also