Lot of times you might think to change the contents of the email, after you hit the send button. But there are no undo buttons in case of sent emails elsewhere rather then Gmail. By using this hidden Gmail feature, you get back your sent email from your gmail account. So in case you hit the send button a little too soon, you can click undo (CTRL+Z) button within 30 sec of hitting send button and you’re good to go.
> Open Gmail and click on small settings icon on top right corner.
> Select mail settings and go to Labs tab. Search for undo and check the undo send feature, Click save changes.
Next time you hit the send button you can see a undo option for 30 sec. Have Fun!!