Apple ID email
The email address I used for my Apple ID is no longer functional. Do I have to change it, or can I add an email that works?
iPhone 6s, iOS 12
Question marked as
You don't have to change it, but if Apple needs to contact you for something, for example resetting your password, you won't receive the email. A current address is better.
Note the restrictions in the article.
What to do after you change your Apple ID or password - Apple Support I suggest doing this before you change your Apple ID or password.