Shipments to Noth America are quite complex, as Customs might be very restrictive.
Before shipping, it is important to check the restrictions of the country of origin/destination, as well as the documentation required, to avoid unwanted withholding.
Make sure your shipment doesn't include goods displayed in our list Prohibited and non compensation items.
Most customs offices have a website where you can find all the details necessary for your shipment to be processed without issues: restrictions, documentation, specific regulations, etc.
Here’s a list of links to the main customs offices, where you can check all the information you need for sending your parcels: