If you are in a European country and you purchase any service at turboSMTP via 2Checkout (formerly Avangate), it is necessary that your VAT is registered on VIES, as provided by applicable law.
In fact, being 2Checkout our official reseller based in the Netherlands, using it produces an intra-European purchasing. For this reason it is necessary to subscribe to the VIES.
For all the information on this page refer to the VIES FAQ.
Alternatively, you can purchase as a private customer. To do that, you should empty all company information fields (that you can find under the switch business/private) before actually switching to the private payment.