All mailing list managers have this issue. If they put footers, you can
notice they are likely to mangle the From header for people with DKIM
signatures on their domain. The alternative is to remove signatures or
just ignore them and this is a recipe to categorized as spam.
They could resend the messages, instead of just forwarding them and modifying them on the fly.
They can DKIM sign a message only if the original message that they received was properly signed (with DKIM).
We had this discussion two years ago:
https://lists.debian.org/debian-project/2020/04/msg00074.html. I think
it went nowhere for the usual reasons (no opinion, just FI, so that you
know people you should get in touch with).
What happened? The last message seemed promising:
By the way, I don't intend to get in touch with anyone, if no-one wants to get in touch with me.
I can also add that:
- It is difficult to follow such a thread of discussion in a mailing list archive. It could have been much easier if the discussion was on discourse.
- It is almost impossible for me to add anything to the discussion now (later), since I was not subscribed to the mailing list when the discussion was happening, and I don't have the emails (to which I can reply).
- It is obvious that some of the messages on the discussion were clearly off topic. It could be beneficial if they were purged from that thread, or moved to some other thread. Personally, I would trust the judgment of the moderators on which messages were off topic.
I would count these as advantages of using Discourse over a mailing list, but I don't want to start another debate on this issue.
I also noticed that mailing lists are sometimes used for making "democratic" decisions. I think that they are not suitable for this purpose and software like LiquidFeedback might be much better:
https://liquidfeedback.com/en/