Many of us use emails as way of keeping in contact with friends or family. Some of us also use it for business. The only thing with email is that there is no way to tell if that email you sent has actually been opened.
However now there is a way for you to tell when that email you sent has been opened, and it'll even tell you where it has been opened - pretty creepy.
The extension will put the email on a map giving the user the approximate location where the recipient has opened the email.
The recipient doesn't need to have Streak installed for it to tell you when and where it's been opened. But they will be notified that they are being tracked.
Streak was mainly designed for businesses to aid in customer relations. But anyone can use it as it's free to install.