Mailboy is a free email tracking extension designed specifically for Gmail users, allowing them to monitor when their emails are opened. This tool provides real-time notifications, helping users stay informed about the status of their sent messages. Mailboy integrates seamlessly into Gmail, appearing in both the email composition window and the thread list, where it displays icons indicating whether emails have been read.

One of the key features of Mailboy is its commitment to user privacy. The extension does not access or store emails, nor does it require permission to manage them. Instead, it utilizes an invisible image embedded in emails to track opens without compromising user data. This ensures that users can track their emails without worrying about privacy violations or data sharing with third parties.