Here you are going to learn about how to undo send Gmail before cancellation period time expires. You got only 30 seconds to revoke your last email. If you won’t move fast enough then all hell breaks loose.
How To Unsend Gmail
1. Login -> Gmail account
2. Click -> Top corner tab
3. Select -> Settings button
4. Open -> General page
5. Check -> ‘Enable Undo Send’ box
6. Set -> Cancellation period as ’30 seconds’
7. Click -> Save button
Now confirm it through send an email and see ‘Undo’ button that was added to the default notification. This ‘Undo’option is available for 30 seconds where you hit send button.