There’re many times, when we wish to “undo a send email,” but you cann’t undo a web-based email, because once you click “send” it just pass through the server. Google has introduced a Gmail Labs feature called “undo send,” that can't pull back an email that's already gone; but holds your message for five seconds so you have a chance to hit the panic button. Just turn it on, in Gmail Labs under Settings, and you’ll see a new “Undo” link on every sent mail confirmation. Click “Undo,” and we’ll grab the message before it’s sent and take you right back to compose. If keyboard shortcuts are enabled in your Gmail account, a better option than clicking on "undo" is to press "z". When you undo sending a mail, Gmail saves it as a draft and you can continue editing the message or discard it.