Recover unsent, incorrectly addressed email

I accidently left a letter out of an email address and tried to send it. The Server rejected it and the Outbox is showing an up arrow as though it’s still trying to send. I’d like to recover it and correctly address it so I don’t have to retype it.

The Outbox is empty and it’s not in the Trash.

It’s not the end of the world. I’d just like to know if it can be done. A search on line just brings up third party software. Not what I want.Thanks for any input.

Are you using Apple Mail?

Sorry Richard,
Seems I didn’t check back so I must have retyped it.That’s embarrassing. (Can’t get used to not being notified of replies).
It would be useful to know how to do that in case it happens again.
I use the Mail program that comes with Mac OS and Optus ISP so have a mixture of email addresses.Thank you.