Open Gmail
Click the email you sent in the last few seconds
Look for “Message sent” at the bottom-left
Click “Undo”
If “Undo” isn’t available, the email can’t be unsent
To enable Undo Send for future emails: open Gmail settings
Click “See all settings”
Go to “General”
Find “Undo Send”
Select a cancellation period (5, 10, 20, or 30 seconds)
Click “Save Changes”