Cathy asked: In gmail, can I un-send a message?
What do you think? The answer is yes, but, you have to enable the option first.
On your computer, open Gmail and go to Settings. On the left menu look for the “Undo Send” section and click, “Enable Undo Send” Specify the amount of time you want to decide if you want to un-send a message. Don’t forget to click Save Changes at the bottom of the page.
Once you have enabled the feature, after sending a message you will receive a notice that “Your message has been sent” with the option to Undo it.
This hidden feature gives you some protection from sending emails too quickly.