When creating a new back in stock notification, if the user is logged in and doesn't have an email set, we allow the user to enter an email and are sending it in the form, in the field NotificationEmail. But that email gets ignored and it tries to send the notification to the user email and fails because it doesn't exist.
If the user is not logged in the email entered, and send in the NotificationEmail, is used and the notification email is sent.
DW version: 9.13.16
