When using the default logging message sender, you should see this notification on code startup:
Using LoggingMessageSender: Do not use in production!
These logs can (and in production should) be disabled by setting the property broadleaf.notification.default-notification-handler.enabled to false. This property also controls the bean for default notification handling.
If actual emails are getting sent (or attempted), setting the above property will also disable them. The beans for logging and sending the emails can be found in com.broadleafcommerce.notification.service.autoconfigure.NotificationServiceAutoConfiguration. The bean for “defaultNotificationHandler” can be either completely disabled with the above property or overridden to instead use a different default message type, like SMS.