What if my customers items were delivered to an EU address? /

The delivery address of your customers items is irrelevant for a VAT refund. Relevant for refunding VAT is proof of export to a country outside the EU or the presence of a certificate of VAT exemption bij an authorised government body.

If the export of the goods and your customers non-EU residency has been checked by customsyou are allowed by the tax administration to refund VAT. 

You can read more about export and customs procedures here.