On Sat, 09 Jan 2016 12:36:08 -0600, Michael Catanzaro wrote:
I, Michael Catanzaro, have never in my entire life seen any email
client display mail headers. It's beyond unreasonable to suggest users
look there for anything, much less for a way to unsubscribe from a
mailing list.
The smarter mail client would NOT display those headers, but would offer
features that do something useful based on whether those headers are
found.
For example, Claws Mail offers a "Message > Mailing-List" menu with
entries like "Post", "Unsubscribe", "Help", "View
Archive", "Contact
owner".