Inbox by Gmail: Say adios to “Oops” with Undo Send

That moment when you press send and immediately realize you made a terrible mistake. But it's too late. We all need to travel back a few seconds every once in a while, so with Inbox you can take back an email right after sending. Undo Send in Inbox launched a few weeks ago, and now it’s available on Android, iOS and the web. So enjoy those second chances!

Source: Gmail Blog