We (A&A) email invoices. We always have (though, once upon a time you could have them faxed). What is relevant here is that we don't post a paper invoice to people - they are always sent electronically.
Indeed, I was recently made aware that my accounts staff are routinely posting invoices to a dozen or so customers every month. This should not be happening, not without an admin fee for doing so. We issue thousands of invoices a month and printing/posting them would significantly impact our business model. It is unnecessary and obviously has an environmental impact as well.
Emailing invoices is something we have done for a very long time, and we have had the occasional complaint. We do take a lot of care, ensuring the plain text email meets the requirements, and even digitally signing them so as to meet EU requirements. We attach a PDF so that a clean print can be made if a paper copy is required internally, and as the first ever "print" of the invoice it is the "original paper copy". We can even attach XML data. We also have a secure web site to access in HTML, PDF, or XML as needed. We could not do more to help people if we tried.
Oddly, it was whilst posting about www.legislation.gov.uk not updating SIs that I spotted a snag that may have affected this from 2 years ago.
Section 13A of The Value Added Tax Regulations 1995 as added by section 5 of The Value Added Tax (Amendment) (No. 6) Regulations 2003 and as modified by section 2(4)(b) The Value Added Tax (Amendment) (No. 3) Regulations 2012
states "The document is not to be treated as the VAT invoice required
to be provided by the supplier under regulation 13(1) unless the use of
the electronic invoice is accepted by the customer" which appears to
contradict scheduled 11 section 3(1) of the Value Added Tax Act 1994 which states "For the purposes of any provision contained in or having effect under
this Act which relates to VAT invoices a person shall be treated as
issuing, or as providing another person with, a VAT invoice if the
requisite particulars are recorded in a computer and transmitted by
electronic means and without the delivery of any document".
Those "regulations" are Statutory Instruments (SIs) which are secondary legislation (easier to pass than the primary legislation, i.e. Acts).
My understanding is that Acts give power to SIs in the first place. If the Act states "For the purposes of any provision contained in or having effect under
this Act which relates to VAT invoices..." then it is stating that the text in those SIs is read in that context. So the Act trumps the SI.
Basically, the SIs seem to state that we can only legally meet our requirement to send a VAT invoice if "the use of
the electronic invoice is accepted by the customer" which means a customer can insist on a paper copy. By the way, I see nothing saying that supplying a VAT invoice on paper has to be "free".
But the Act, in scheduled 11 section 3(1), is clear that we have met our obligations by sending the invoice electronically.
So I believe that a supplier can insist on sending invoices only by electronic means, and meet the legal requirements for issue of a VAT invoice, and that a customer cannot insist on a VAT invoice "on paper".
What we need is HMRC to make a clear statement to that effect.