Google has added a new Gmail labs component that allows users to “Undo Send” an email for a few seconds after the message sends.
Once the feature is activated, a new “Undo” link will appear next to every sent email confirmation notice. When clicked, the “Undo” will take you back to the composing window confirm the retrieval of the email and allow you to edit it further.
However, “Undo Send” doesn’t really recall a message that has been already sent. The feature only holds emails in a queue for five seconds, giving you time for second thoughts. I personally wish it was available to more like 1 minute after you click send.
To enable it, log in to your Google Gmail account. At the very top of your Gmail Inbox, you will see a green chemical flask (). This will bring up the Google Gmail Labs experimental area. About 3 quarters of the way down the page you will “Undo Send.”