In previous versions of Shift4Shop - when adding a customer record through a phone order - the store would create a "dummy" email address as a placeholder on the customer record. This was intended so that you could create the customer record and complete the Phone Order quickly. However, the expectation was that you would enter the correct email address before placing the actual order since the email address created by the store was merely a placeholder.
Unfortunately, we removed this functionality due to email compliance issues. In many cases, the merchant left the placeholder email address unedited, and the order would trigger bounce-back emails that affected the email deliverability of the store and impacted server performance.
As of the current versions of Shift4Shop, you must enter a proper email address when creating a new customer record on your phone orders.