A store administrator can enable and disable email notifications directly on the notifications listing page in the store Admin area (Store Setup -> Email Notifications).
Email notifications are sent separately for every user type enabled in a store. Hence, they can be enabled and disabled on a per-user-type basis.
To enable/disable notifications for a user type, set the corresponding toggle either ON or OFF.

If the ON/OFF toggle is in faded-green, a notification can not be disabled for this type of user.
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