What if Emails were Multilingual?

Multilingual emails

Back when I was a student in Aberystwyth, I used to receive a lot of bilingual emails from the University and its departments¹. I was reminded of this when I received an email this week from CACert, delivered in both English and German.

Wouldn’t it be great if there were some kind of standard for multilingual emails? Your email client or device would maintain an “order of preference” of the languages that you speak, and you’d automatically be shown the content in those languages, starting with the one you’re most-fluent in and working down.

The Web’s already got this functionality², and people have been sending multilingual emails for much longer than they’ve been developing multilingual websites³!

Enter RFC8255!

It turns out that this is a (theoretically) solved problem. RFC8255 defines a mechanism for breaking an email into multiple different languages in a way that a machine can understand and that ought to be backwards-compatible (so people whose email software doesn’t support it yet can still “get by”). Here’s how it works:

1. You add a Content-Type: multipart/multilingual header with a defined boundary marker, just like you would for any other email with multiple “parts” (e.g. with a HTML and a plain text version, or with text content and an attachment).
2. The first section is just a text/plain (or similar) part, containing e.g. some text to explain that this is a multilingual email, and if you’re seeing this then your email client probably doesn’t support them, but you should just be able to scroll down (or else look at the attachments) to find content in the language you read.
3. Subsequent sections have:
   • Content-Disposition: inline, so that for most people using non-compliant email software they can just scroll down until they find a language they can read,
   • Content-Type: message/rfc822, so that an entire message can be embedded (which allows other headers, like the Subject:, to be translated too),
   • a Content-Language: header, specifying the ISO code of the language represented in that section, and
   • optionally, a Content-Translation-Type: header, specifying either original (this is the original text), human (this was translated by a human), or automated (this was the result of machine translation) – this could be used to let a user say e.g. that they’d prefer a human translation to an automated one, given the choice between two second languages.

Let’s see a sample email:

Content-Type: multipart/multilingual;
 boundary=10867f6c7dbe49b2cfc5bf880d888ce1c1f898730130e7968995bea413a65664
To: <b24571@danq.me>
From: <rfc8255test-noreply@danq.link>
Subject: Does your email client support RFC8255?
Mime-Version: 1.0
Date: Fri, 27 Sep 2024 10:06:56 +0000

--10867f6c7dbe49b2cfc5bf880d888ce1c1f898730130e7968995bea413a65664
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain; charset=utf-8

This is a multipart message in multiple languages. Each part says the
same thing but in a different language. If your email client supports
RFC8255, you will see this message in your preferred language out of
those available. Otherwise, you will probably see each language after
one another or else each language in a separate attachment.

--10867f6c7dbe49b2cfc5bf880d888ce1c1f898730130e7968995bea413a65664
Content-Disposition: inline
Content-Type: message/rfc822
Content-Language: en
Content-Translation-Type: original

Subject: Does your email client support RFC8255?
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 7bit
MIME-Version: 1.0

RFC8255 is a standard for sending email in multiple languages. This
is the original email in English. It is embedded alongside the same
content in a number of other languages.

--10867f6c7dbe49b2cfc5bf880d888ce1c1f898730130e7968995bea413a65664
Content-Disposition: inline
Content-Type: message/rfc822
Content-Language: fr
Content-Translation-Type: automated

Subject: Votre client de messagerie prend-il en charge la norme RFC8255?
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 7bit
MIME-Version: 1.0

RFC8255 est une norme permettant d'envoyer des courriers
électroniques dans plusieurs langues. Le présent est le courriel
traduit en français. Il est intégré à côté du même contenu contenu
dans un certain nombre d'autres langues.

--10867f6c7dbe49b2cfc5bf880d888ce1c1f898730130e7968995bea413a65664--

Can I use it?

That proposed standard turns seven years old next month. Sooo… can we start using it?⁴

Turns out… not so much. I discovered that NeoMutt supports it:

Support in other clients is… variable.

A reasonable number of them don’t understand the multilingual directives but still show the email in a way that doesn’t suck:

Some shoot for the stars but blow up on the launch pad:

Others still seem to be actively trying to make life harder for you:

And still others just shit the bed at the idea that you might read an email like this one:

That’s just the clients I’ve tested, but I can’t imagine that others are much different. If you give it a go yourself with something I’ve not tried, then let me know!

I guess this means that standardised multilingual emails might be forever resigned to the “nice to have but it never took off so we went in a different direction” corner of the Internet, along with the <keygen> HTML element and the concept of privacy.