gmail client browswer Open Gmail in Chrome. Press Ctrl+Shift+J (Windows) or Cmd+Opt+J (Mac) to open Chrome’s built-in JavaScript console. Paste the following into the console and press Enter: navigator.registerProtocolHandler(“mailto”, “https://mail.google.com/mail/?extsrc=mailto&url=%s”, “Gmail”); Chrome will prompt you, asking if you’d like to “Allow Gmail (mail.google.com) to open all email links?” Click the Use Gmail button. That’s it!