Sometimes it is the firstname that changes.
Example: Kiley Smith was written on the initial paperwork for us to make the account but they tell us a month later that their firstname is actually Kileyee or something.
Sometimes it is the last name that changes
Kiley Smith is now Kiley Doe
It is our practice to make the old misspelled/changed name email an alias to the new one. That way if anyone was emailing the old email they would still get it. Since we sync to on prem AD we have to do this with proxyaddresses and uppercase and lowercase (smtp SMTP)
Also the new email would usually be formed by the new name. Kiley Smith is now Kiley Doe
So her email would be email@example.com
Her alias would be her old email firstname.lastname@example.org
This would also need to chage their AD username/login name and UPN