Gmail and some other clients support it, more details here
https://sendgrid.com/blog/list-unsubscribe/
<https://sendgrid.com/blog/list-unsubscribe/#:~:text=List%2Dunsubscribe%20is%20an%20optional,sender%20as%20spam%20or%20junk.>

Regards,

Yawar

On Mon, Jan 4, 2021 at 2:52 PM Daniil Baturin <daniil@baturin.org> wrote:

> Looks like GMail (or something else in the middle) indeed messes with
> headers.
>
> I get the correct headers in the messages received by a self-hosted
> Postfix:
>
> List-Id: <caml-list.inria.fr>
> List-Help: <mailto:sympa_inria@inria.fr?subject=help>
> List-Subscribe: <mailto:sympa_inria@inria.fr
> ?subject=subscribe%20caml-list>
> List-Unsubscribe: <mailto:sympa_inria@inria.fr
> ?subject=unsubscribe%20caml-list>
> List-Post: <mailto:caml-list@inria.fr>
> List-Owner: <mailto:caml-list-request@inria.fr>
> List-Archive: <http://sympa.inria.fr/sympa/arc/caml-list>
>
> However, Thunderbird doesn't seem to offer an unsubscribe option based on
> that header, and I can't remember any email client where I'd have seen that
> functionality.
>
>
> On 1/5/21 2:42 AM, Yawar Amin wrote:
> > Actually, this is puzzling indeed–I notice there's no
> > 'List-Unsubscribe' header in the messages that reach my Gmail inbox,
> > but it _is_ present in the message that gets archived at
> > e.g.
> https://inbox.ocaml.org/caml-list/CAH=h3gEOoMUBezUb3NoXvksX34ke3etP8=aScYeCzRc9p-ehrg@mail.gmail.com/raw
> > <
> https://inbox.ocaml.org/caml-list/CAH=h3gEOoMUBezUb3NoXvksX34ke3etP8=aScYeCzRc9p-ehrg@mail.gmail.com/raw
> >
> >
> >
> > And in fact Gmail is not showing the 'unsubscribe' UI that it normally
> > would if it found the 'List-Unsubscribe' header. Looks like something
> > is stripping out the 'List-*' and perhaps other headers before
> > delivering them to Gmail.
> >
> > Regards,
> >
> > Yawar
>
>