Gmail users should know about this little-noticed feature

Gmail’s Undo Send feature gives users a brief chance to stop an email after pressing Send, which can help catch a typo or add missing information. The feature delays dispatch rather than retrieving a message that has already reached the recipient.

The default cancellation period is five seconds, but Gmail users can extend it to 10, 20 or 30 seconds in desktop settings. To change it, open See all settings, find Undo Send under General, choose a period and save the changes; opening the message can end the chance to undo it early.