Your inbox will never look the same after this.

A San Francisco-based startup called Streak has developed a free Google Chrome browser extension that's changing the email game: the extension lets email senders see when recipients open an email.

Using the extension with a Gmail account, senders will be notified when someone opened their email and who opened the email.

If that's not useful — or for some, disturbing — enough, Streak will also tell you where the email was opened. The extension will put the email on a map, giving the user real-time location updates about the recipients.

An eye icon will appear when a user views an email sent with Streak. When the recipient opens the email, the eye icon will turn green, signaling the sender that their email has been read. The recipient doesn’t need to have Streak installed for the email sender to be notified that the email was opened.

The sent email will not notify the recipient that their email is being tracked. Streak isn't the first service to perform this function; Bananatag also notifies a user when their email has been read, but requires a monthly fee to send more than 5 emails, and doesn't give you locations.

Streak was designed for customer relationship management, and also features tools for sales, support, hiring, scheduling emails and sharing emails company-wide. It also works with Gmail in the Safari browser, as well as Google Apps accounts for businesses.

Streak is free while in beta; the developers plan to maintain a free version of the extension as it continues in development.