When is an e-invoice not an e-invoice? 10 years ago it was simple. It was clear that a "true" or "pure" electronic invoice was a structured computer-to-computer message. The supplier's computer would send an invoice message in a format that the customer's computer could read. An email with a Word document or an excel file attached was not an electronic invoice and worse, a pdf image of a paper invoice was nowhere near an e-invoice. These were superficial attempts to tick the e-invoicing box. They weren't true electronic invoices. But in recent years the line between what is and what is not an e-invoice has become blurred and the "purity" of the "true" electronic invoice is becoming it's own worst enemy.