I'm think you can set up notifications like this with After Ship. I haven't used it in awhile but I remember it being pretty powerful, pretty sure you can do this.
Song Fei here from TrackingMore Team. We develop a tracking page app for shopify store which allows user to send email to buyer when shipping status change to "delivery"
This app support 652 couriers worldwide. And it sort all shipping status into 7 status.
Pending, a tracking number is created but has not scanned by courier.
Out for delivery
Exception, loss, damage, return to shipper, etc.
This app will track your tracking number automatically, and when shipping status changes, it will send email notification.
It can send emails to sellers or buyers based on user's setting.
And all email content can be customized.
You may want to find more introduce here: https://apps.shopify.com/trackingmore?utm_source=shopifyforum&utm_medium=forum&utm_campaign=songfei