Certainly many people using e-mail services when sending messages forgot something important or accidentally sent an email to the wrong addressee. In this situation, there was no other solution than sending another email with apologies and fixing the mistake made before. It seems that Google has come up with a solution that will solve this problem. However, there is a catch - the solution will work only for users which use e-mail service developed by Google - Gmail.
After sending an e-mail from phone with Android system Gmail app always shows short communique that our message was sent. After update of Gmail this window was extended, and next to published text we can find a button with "undo" text. During first seconds after sending our mail by tapping "undo" button we may cancel sending of our message. When we will decide for this decision, then Gmail app will again open us a window where we will have option of making changes in our mail. If you want to use this function you must have official Gmail app in 8.7 version or higher.