Improve mailing-list footers
I think we could replace the default Mailman footer by something much more helpful. On each mailing lists, I believe it would be useful to say something like:
To unsubscribe, please visit: https://... Anyone can subscribe to this list, archives are publicly available at: https://..
Or something like:
This list is not archived. Please respect the privacy of this channel and always ask before sharing emails to outsiders.