On Sun, 2019-11-24 at 11:34 +0100, Narcis Garcia via GNUzilla bug
reports wrote:
> Please list administrators:
> Add some visible sign to these mails to distinguish that them come
> by bug-gnuzilla.

Please see 
https://lists.gnu.org/archive/html/bug-gnuzilla/2019-10/msg00006.html

Mailman does add the List-id header, indicating 

List-id: GNUzilla bug reports <bug-gnuzilla.gnu.org>

Which should make it possible for your mail program to do whatever one
wants with such messages.