GMail Labs has added yet another really nice feature. Now you can cancel the delivery of any email, once you have sent your mail. This really helps at times, say you have two persons A and B with the same name and you just have mailed a very confidential information whaich was meant for person A, to the other person B. It would have too late had Gmail not introduced this feature in Gmail Labs called Undo Send. Well, this can be done in other gmail ways too!
To enable Undo Send, all you need to do is click on your settings tab and then on the settings page, click on Labs. From the list of Lab features, select Undo Send and set it to enable. Save your settings. Now onwards when you send an email, you will notice a Undo link next to the message that says "you email has been sent". This feature will not pull back an email that's already been sent, but it just holds your email message for five seconds, so you have a chance to hit the Undo Send button and cancel the delivery of the email. The Undo button vanishes automatically after five seconds. Remember, the duration is 5 seconds only. So in case you hit the Undo Send button after 5 seconds your email might already have been delivered.