Now, Gmail is officially giving users an option to correct such missteps.
The New York Times explains:
After years of experimenting with it as a Labs feature, Google announced that it was formally adding an “undo send” option for web-based Gmail users. (If you are a repeat offender on mobile, the Inbox app also has an undo feature.) The new tool allows users to choose a delay time from 5 to 30 seconds in case of a change of heart.