Don't Send Shipment Notification Based On Conditions
Make 'Don't Send Shipment Notification' an option in filter/automation rules.
We use Shipstation to send our catalog. Customer does not need an email notifying them their catalog is on the way. But we do want customer's email associated with their catalog shipment as customer id, so don't want to change email to an internal address and would rather than not disable notification on a shipment by shipment basis if it can be automated.