I work for a company that provides a fax-to-email (and email-to-fax) service. I'm not going to reveal how popular it is - but I am going to detail two reasons people continue to use fax in 2021 that aren't just the uncharitable “people are luddites” explanation. This is all anecdotal knowledge I've picked up from maintaining such a service and talking to customers about it. Don't take it as gospel, and certainly don't take it as legal advice.
Is fax really that awful? Well, yes, it is. But there are many fax machines in the world, and for the most part, they've worked without issue for decades, and continue working to this day. This is of course made possible by all fax machines implementing common standards for transmission and receipt.
The particular standards implemented are usually indicated in terms of Groups. Group 1, Group 2, Group 3, and Group 4. While Group 1 fax machines are not interoprable with Group 2, and have been long removed from use - Group 2 machines (introduced in 1976) remain interoperable with Group 3 machines, and can still (seldomly) be found in the wild to this day. That's 45 years of service!
It wouldn't be until 5 years later (1981) that what we know as SMTP would take root. uuencode and binhex appear as ways to send files and text encoded in non-ASCII formats. UTF-7 is summoned in a dark ritual. Ultimately it takes 15 years (1996) for MIME to appear, detailed in RFC2045. For the entire duration of development of the humble email, fax provided a simple and unencumbered method of sending a document with no concern on the part of the user in terms of preservation of presentation or locale.
It works. And it will almost certainly continue to work for the next 45 years - even as telecoms operators cease providing an analogue telephony service on the end of the cable and instead offer SIP with g711/a RTP. That counts for a lot.
So fax is (largely) reliable, and if you already use it, there's an argument as to whether you should bother switching. But email is reliable too. I run my own mail server and feel qualified to say that email, if anything, is more reliable than fax. So why do I see customers taking up a fax service in 2021?
Well, it might have something to do with the law, and what constitutes a acceptance of a contract. Prior to fax, the common technology used for transmission of legal documents, such as court orders, was Telex. This was entirely because Telex had two properties:
Telex was instantaneous. In English law, if I receieve a contract, sign it, and then post it back, the contract applies from the moment I posted it - not from the moment the other party receives it. This is the “postal rule”, and is of some advantage to me in that I can be sure the contract was binding when I posted it, rather than upon receipt of confirmation from the party that sent it to me. No matter how long the postman takes, the contract is already binding. This, however, isn't great for the other party. They don't know whether the contract is active until they receieve my response. Telex being ‘instant’ did away with the problem altogether - much better for your business.
The other property Telex provided was that the sender would receieve an “answerback”. Essentially confirmation from the recipient that the document had been received. A property not only desirable, but necessary in certain circumstances. Also much better for business too.
As fax developed, it went through the same discussions email is still going through today. For fax, a key question was whether if someone receives a fax, is it equivalent to a posted document or a Telex? The view that fax is a suitable replacement for Telex was not quite settled even as late as 2002. Although it does appear to be now, given BT deprecated their Telex offering many years ago.
So, we can maybe presume receipt of a fax is akin to receipt of a Telex, rather than receipt of a letter, and keeps the properties of being ‘instant’ and having confirmation of receipt. Again, IANAL. But what about email?
Well. Email isn't instantaneous. Even when the recipient MTA gives you a 2XX code, it doesn't mean the mail has been received. Filters, milters and relaying can happen once your mail is accepted for ‘delivery’ - receipt is one possible outcome.
We end up with a lot of questions:
The list goes on, and is the crux of the problem. There's a lot of questions. Some of them we have answers for today; for some others we'll see answers eventually. In the case of fax, not every question was settled in English law before it replaced Telex, so it's possible we might just have to wonder about question 2 or 4 forever. But with or without them answered, the ambiguity around email and the longevity of fax technology remain to me as the only two reasons people are using fax in 2021.