Undo Send, was just recently added to ‘Inbox for Gmail’ for Android, after been a long popular Google Labs feature. The company says that the feature, will allow users to cancel the sending of an email within a pre-specified number of seconds after the email is sent, will be publicly allowed to all Gmail users online.
Undo Send’ allows people using Gmail to cancel a sent email if they have second thoughts immediately after sending. The feature is turned off by default for those not currently using the Labs version, and can be enabled from the General tab in Gmail settings.
This feature is found just heading over to the settings page within Gmail and navigate to General tab. If this feature has been pushed to your account you’ll be allowed to ‘Enable Undo Send’ and click a cancellation period, which can be 5,10, 20 or 30 seconds. As any other action in Gmail, the ability to unsend the email will appear along the top of the screen on the ‘Your message has been sent’ notification pop up.