How to get rid of an unsent email.

After the iOS 16.1.1 update, an email that is months old is now showing up as an unsent email. I open the mail app, choose Outbox and delete the mail. A few minutes later, it’s back, and not only is it back, but the number of unsent emails in the mail app keeps increasing even though there is only one unsent mail in outbox. I have tried deleting from outbox, and rebooting. Nothing works. Is anybody else having this issue, and have you found a work around?