[Users] Email subject encoding (Was: CRLF in subject)

[Jeffrey Walton]

On Sun, Jan 22, 2023 at 5:47 AM Cristian Secară <liste at secarica.ro> wrote:
>
> În data de Sat, 21 Jan 2023 21:01:58 +0000, Marco a scris:
>
> > But in Claws-Mail it looks like 2 spaces if the subject line is shown
> > in one line in the message window. Is that intended?
>
> This could be a bug propagated from Sylpheed code. It occurs whenever the subject (including the "Subject:" word) is longer than whatever RFC-related standard.
>
> Your subject:
> Intel J4125M - ausreichend für Videokonferenzen mit BBB?
>
> After sending with Claws Mail:
> Subject: Intel J4125M - ausreichend =?UTF-8?B?ZsO8cg==?= Videokonferenzen
>  mit BBB?
>
> After sending with RoundCube:
> Subject: =?UTF-8?Q?Intel_J4125M_-_ausreichend_f=C3=BCr_Videokonferenzen_m?=
>  =?UTF-8?Q?it_BBB=3F?=
>
> After sending Thunderbird:
> Subject: =?UTF-8?Q?Intel_J4125M_-_ausreichend_f=c3=bcr_Videokonferenzen_mit_?=
>  =?UTF-8?Q?BBB=3f?=

Please forgive my ignorance... I noticed GMail uses the '?utf-8...'
encoding when exporting email messages. I have not been able to locate
the standard that specifies that encoding method.

Which standard governs the use of the '?utf-8...' encoding method?

Thanks in advance.