There are two cases where it is generally necessary to change the email address.
1. The email address I entered is incorrect
If the entered email does not exist and has therefore never been delivered, it turns purple and goes into the standby emails (along with emails not delivered for other reasons, such as a full inbox). In this case, you can change the email address yourself.
If, instead, the email remains black along with the others, it means that the email address exists and has been delivered to someone we probably don’t know. In this case, it cannot be modified independently, and you must contact support.
2. My customer’s email address has changed
It is not possible to change it independently, and you must contact support via email.