Protonmail has this:
"Catch an embarrassing typo after you hit send? Our new Undo Send feature is now in beta in the web app and is enabled by default for all users, including Free users. Undo Send gives you a chance to correct your message after hitting send. ItÆs set to a 10-second delay by default, but you can also choose 5 or 20 seconds."
--- SBBSecho 3.14-Linux
* Origin: The Rusty MailBox - Penticton, BC Canada (1:153/757.2)