We all regret hitting that "send" button every once in a while—maybe we'll forget an attachment, CC the wrong person, or spot a typo at the last second. And unless you happen to have an admin login to the recipient's POP server, there's usually not much you can do about it.
Google aims to change that with a new experimental Gmail feature. While the company hasn't yet found a way to teleport messages out of existence once they're actually sent, the "Undo Send" feature does give users five seconds to click "Undo" and prevent a message from going out. Google User Experience Designer Michael Leggett explains his approach in a blog post about the addition:
An email to the wrong Larry pushed me over the edge. I could undo just about any other action in Gmail — why couldn't I undo send? Many people agreed, including Yuzo Fujishima, an engineer in the Tokyo office. My theory (which others shared) was that even just five seconds would be enough time to catch most of those regrettable emails.
Gmail users can enable the feature by popping into Gmail's Labs settings pane and hitting the "Enable" radio button next to "Undo Send." E-mailing under the influence is probably inadvisable either way, though.