Due to stricter custom rules it's not allowed to ship alcohol to countries outside the EU with PostNL and other couriers as it's considered as dangerous goods. In most cases these shipments are x-rayed, and returned or even destroyed. So it's a big risk to use PostNL
At this moment with DHL express most shipments are going all-right, so better use them. https://www.dhl.com/en/express.html