Return to sender is a free Chrome extension developed by spirodonfl that aims to enhance email security. This add-on checks email addresses in the "TO", "CC", and "BCC" fields against a crowdsourced database to determine if they have been flagged as risky. When using this extension in the regular Google Mail web interface, it automatically runs in the background.

The main feature of Return to sender is the ability to identify risky email addresses. If an email address has been flagged as "Risky", a colored box will appear next to the email, indicating the level of risk. Users can simply glance at their email interface to quickly assess the safety of the addresses they are about to send messages to.

In addition to the risk indicator, users can also click on the colored box to view details about the flagged email and even flag an email themselves if they believe it poses a risk. This allows users to contribute to the crowdsourced database and help others identify potentially dangerous email addresses.

Return to sender has some exciting upcoming features planned, including integration with the new Google Inbox, an updated look and feel, the option to scan emails already sent for risk factors, as well as extensions for Safari, Firefox, Outlook, Thunderbird, and other popular email clients. These upcoming features will further enhance the email security offered by this Chrome extension.

Stay ahead of email risks with Return to sender, the Chrome extension that checks email addresses for potential risks before you hit send.