If you shall export goods from the Netherlands you must always declare the goods to Dutch Customs
You can not send goods from the Netherlands to outside of the EU before Dutch Customs has given its permission. As an exporter you are required to notify the Dutch authorities via a customs clearance - also called a declaration. Dutch Customs controls the declaration via a customs clearance, then you can send the goods out of the country.
Here you will find more detailed information about customs clearance of exports.
The main areas for export duty:
Certain goods, even under a value of EUR 200.00, must clear customs regardless. Read more about restricted goods for export here.
Customs clearance documentation:
As an exporter you are responsible for labelling and addressing the goods correctly, and providing the correct customs clearance documentation.