E-invoicing will become mandatory across the EU and in most cases this will be via Peppol. Outside of Europe more countries are makign e-invoicing mandatory.
Know that you can also use Billit to exchange invoces networks other than Peppol, such as the SDI network in Italy, etc. You can find a complete list of available countries in this country list.
If the country you're looking for is not in the list please contact us.