How To Unsend An Email
1.) Click that weird gadget icon in the top right corner of Gmail, then mouse down to “Settings.”
2.) Then click to “Labs.” Search for the lab feature titled “Undo Send.” Enable it, and click “Save changes.”
3.) Still in “Settings,” go to “General,” and scroll down to the “Undo Send” section. Enable it there too.
Now every time you send an email, a yellow bar will pop up and give you the chance to click undo. So next time you accidentally email that picture to your entire family instead of that girl you like, you can undo it.