Get back your sent Mail instantly and sent undo in Gmail .

You sand a mail to some one but after sent the mail you think there is some thing wrong in your mail. But you have nothing to do . But this time you can UNDO your sent mail instantly . Here the sequence are given to enable UNDO sent mail .
1. Go to Setting
2. Enable Undo send with 10 second .
3. Click Save Change button . 

Now you can see UNDO after sent every mail .When you was "Your message has been sent " .

Thank you .