Gmail offers a Lab called “Undo Send.”
Today, I made use of this handy feature at least 3 times; once when I accidentally sent an email to the wrong person; another time when I clicked send before I was really ready to; and then again when I realized my grammar was a bit off.
You can find it by clicking on the green beaker at the top right of your screen, enabling it and then clicking “Save Changes.”
Then, when I click Send, I see a note popup under the thread of the email I just sent. (Assuming I didn’t click “Send and Archive.” If I did, the note would appear at the top of my screen.)
Then, you can customize how long it gives you to realize your mistake. Go to Settings > General > Undo Send. I give myself 10 seconds, just to be safe.
Yet another way to prevent those “d’Oh!” moments.