Failsafe tip
The last thing to add to an important email is the email address.
Write the thing, save it as a draft, and, an hour later, put the email address in and then hit send.
It's not clear that you should send an important text, but if you're going to, write it in a notes app, then copy, paste and send.
Send it when you're ready, not before.
There's no 'recall' button.