This is unheard of in the history of email: You can activate a secret feature in Gmail that allows you to un-send a message. I simply don’t believe it.
And, of course, I’m correct: Once email is sent, it can’t be un-sent. So all the Gmail delay feature does is simply postpone sending a message. You’re given the option of setting that time window. After it expires, the message is sent. No way to recall it then.
I don’t know how many times I’ve yearned for such a feature. It’s taken a few years, but I’ve finally honed the art of not writing an email while I’m angry — or at least of not sending the email right away.
Another option, and a feature of all email programs, is simply to save a message in the Drafts folder. From there, you can resurrect the message, edit it a tad, or just decide whether or not it’s worthy to send.