For example, when you created your Apple ID, you were in a state of passion and used unsafe mail or mail with an "ugly" address; or, perhaps, this is a very old mailbox and access to it has been lost.
- go to Settings → your name → "Name, phone numbers, e-mail";
- for Mac: Settings → Apple ID → " Name, phone numbers, e-mail»;
- the device may ask for answers to security questions or an account password;
- in the "Contact details" section, click "Edit" → "Add e-mail or phone number" → "Add an email address»;
- enter the email address of the mailbox that you want to use for your Apple ID. a verification code will be sent to it, which you will also enter in the next step;
- now you will see two mailboxes in the "Contact details" section - the old one and the new one;
- click "Edit" again and delete the old mailbox marked "Apple ID". in this action, the device will ask you to select a new email address for Apple ID - choose the address you just added.
Your Apple ID is now linked to your new email address.
By the way. If you used iMessage and FaceTime not by phone number, but only through the Apple ID email address, then don't forget to tell your new email address to the necessary contacts-they will no longer get through to the old address.