No, it hasn't, and there are very specific(& V expensive) requirements for emailing invoices, as well. Before I retired it was something that I investigated at great length: By that time, invoices were our only outgoing mail and junk mail*, our only incoming mail.

*To this day every publisher sends you a copy of the publication your advertisement appeared in, and some agencies have a whole department to check, cut out and send them to the client. In job advertising it's simpler, if you don't get any replies then we'll investigate, so for over 20 years, we binned forests of newsprint: 10 ads. in one paper; 10 copies of the newspaper! Only in recent years have we been able to arrange for recycling, but it's still a waste of resource, not to mention mailing costs.