Have you ever sent an email and just after hitting the Send button realized with horror that you sent the mail to the wrong person? At other times you realize an error within the mail or a misspelling.
A new Gmail lab feature now gives you a chance to stop the mail from going out and saves you from sending a follow up mail to apologize for your mistake. Turn on Undo Send in Gmail Labs under Settings, and every time you send an email you will see a new “Undo” link on the sent mail confirmation message. But you have to be quick, because the Undo link works for only 5 seconds.
This feature cannot pull back the mail that’s already gone, but give you enough time to hit the panic button. You must recall that Gmail provides you two more features that prevents you from sending mails that you later regret - the Gmail Goggles that prevents you from sending drunken mails and the Forgotten Attachment Detector that reminds you when you forget to attach the files you said you going to in the mail.
[via Official Gmail Blog]