Re: Mailing list etiquette: plain text, please
On 2015-09-26 14:45:29 -0600, Nelson H. F. Beebe wrote:
> Recently, there have been several postings to this list in encoding
> base64, which means that the mail body contains unintelligible text
> like this:
>
> TWVocmFuLA0KDQpMZXQgbWUgY29....
> Cg0KVGhlIHN0YW5kYXJkIGlzIGr....
> c2hvdWxkIGJlaGF2ZS4gIFRoZSB...
That's also plain text, just encoded in base64 *internally*. Mail
software is required to support base64 decoding, so that users
should never see this encoding.
Now, I agree that base64 encoding should not be used, because that's
unnecessary, it takes more space, and yields problems with antispam
software.
> It is important that mail archives be searchable with ordinary
> string-search utilities, so please, check your mail client settings,
> and ensure that future postings appear only in plain ASCII or UTF-8.
There are 3 different things:
1. The media type: it should be text/plain. Providing both text/html
and text/plain (as multipart/alternative) is OK. Providing text/html
alone is not.
2. The charset (which is how individual characters are mapped to
sequences of bytes): it should be ASCII-based, which is the case of
almost all charsets. Given the fact that messages are in English,
thus with no accented characters, I don't think that more restriction
is needed. I personally use iso-8859-1 when possible, since it is
shorter than utf-8, and I don't think there is any problem with it
here (please tell me if there is).
Concerning the allowable characters, it seems that some people on
this list have problems with Unicode math characters, such as:
Infinity: ∞
Less or equal: ≤
Greater or equal: ≥
Intersection: ∩
Double-struck capital R (set of reals): ℝ
So, if I understand correctly, they should be avoided.
3. The Content-Transfer-Encoding (which is how the body and each
attachment are encoded): it should be either 7bit (for ASCII-only
messages) or 8bit, i.e. characters are not encoded internally, so
that one can use string-search utilities without using mail software.
I agree that base64 should be forbidden in this list. The fourth
existing encoding is quoted-printable; for English text, text appears
just like 7bit and 8bit, but the equal character is encoded by "=3D"
(equal character followed by its hex ASCII code 3D), which may be an
issue in this list since we use lots of math. So, this encoding should
be discouraged if possible, but may be unavoidable with some mail
software during the mail transfer.
--
Vincent Lefèvre <vincent@xxxxxxxxxx> - Web: <https://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)