When creating shipments in Magento via the API method salesOrderShipmentCreate the option to send confirmation email is available. But there will be no tracking information available on the shipment. The tracking information is added via salesOrderShipmentAddTrack which don't allow any option to send a shipment confirmation.
This module has been created to address the above problem. Without modifying the API. It's all done by a scheduled script looking for shipments containing tracking information and where no shipping confirmation has been sent to the customer. For every shipment found a shipping confirmation is being sent and the flag saying whether the confirmation has been sent is updated.