[rstuart4133]

> it means that if you forward an email list message to someone else, they can unsubscribe you without your consent as a prank

Surely that is a bug in the email client that forwarded the email. It should have replaced the headers, including List-Unsubscribe, with its own.

That looks to be what's happened in the emails I receive. The one exception would be if someone forwarded an email as an attachment, but in practice almost no one does that.

[kragen]

what does your user interface for interacting with the list-unsubscribe header look like?

[rstuart4133]

I haven't unsubscribed from a list in years, perhaps decades, despite being subscribed to a few. So I can only tell you from memory. In Thunderbird, I believe I've see a "List Unsubscribe" button in the list of actions available, alongside "Reply-All", "Edit as New" and so on.

In GMail I believe senders that have this implemented now have a big blue UNSUBSCRIBE button next to their email address at the top of the message.

Neither appear if the headers aren't there.

[SpaghettiCthulu]

Ideally a big green "Unsubscribe" button. Make it promise cookies too for good measure.