“Well, now you can take advantage of that delay to “undo” the message. (Not to be confused with Gmail Goggles, which is geared more at preventing drunken emails from ever being sent out in the first place). Just enable the feature in Gmail Labs in Settings (Scroll down, it is not at the top for some reason). It only works during that 5 second delay between the time you hit send and the time that Gmail actually sends the message.”