Clearer.io Address Validator

I'd give this app 7 stars if I could. It's super intuitive, has a ton of options to fit your exact need and if you can't figure something out, their support is TOP. They're US based and when I needed something they got on the phone with me until it was resolved perfectly. I got the app because I had a PO box problem (FedEx doesn't ship to PO boxes but customers kept checking out with a PO box), and this is EXACTLY what I needed. It informs the customer they can't check out with a PO box, and stops them from doing so if they try. I needed some additional customization and the Address Validator Team was incredibly helpful. 7 stars.