Don’t worry about typos and misspelling names in emails anymore as Gmail just rolled out the “Undo send” feature for its users. Currently, it is only available on the web but rumors say that it will eventually be available on the mobile app.
To enable this feature, go to settings and in the General tab “enable undo send” then select a cancellation period, which is the delay between hitting the send button and the email being actually sent. You have the option to choose between 5, 10, 20 and 30 seconds.
Save your changes to activate the feature. Now, when you send your email, you will see a message on top that will say: “Your message has been sent. Undo. View Message”. All you have to do is click on the link. The email will be then found in your Drafts folder where you can choose to keep it or delete it.
source:http://www.trendingbytes.com/general_news_2/gmail-finally-lets-you-unsend-emails