One of the reasons for the great success of Gmail, is the amount of innovative features. Certain features have shown that we can save time when reading our emails. One of these features is “Cancel sending an email".
For those who like to live dangerously, they had the chance to try Google Labs, the feature launched in 2009 that gives them the option to cancel email in Gmail.
This functionality does not retrieve messages from the server to “undo” the sending of messages, in fact, it delays sending for 5 seconds or more, giving the chance to cancel the sending or add information to the email.
The feature is officially available, and can be found within Gmail as a fully native feature, without any need to enter settings to activate it.
So, when you're sleepy and send that compromising email, remember that you can edit it a few seconds later. Believe me, it can save lives ...