category is used to classify the different types of notifications.
All the notification sent before a tracker is created. Those notifications are sent using the fulfillment status codes
The package has been shipped by the carrier
The package has had an attempt to be delivered, but the delivery did not succeed
The package has had an incident at some point during delivery
The package is at the pickup point
The package is delivered
All other types of notification like the departure to the destination country, out for delivery, at custom etc.
Notifications triggered when a tracker or an order enters a smart state
Notifications triggered when a tracker or an order enters a severe smart state