Re: [Savannah-hackers-public] DMARC related changes starting this week for FSF hosted Mailman lists

[Ian Kelling]

I have an update on some things.

The change of removing subject prefixes and footers from discussion
lists has been delayed until about a week from now. Partly because we
figured out that savannah group admin emails are more up to date than
the ones stored in Mailman, and they are associated with many mailing
lists. Those notifications will go out today or tomorrow.

The mailman setting to store administrator and moderator email addresses
is poorly designed because then you get automated LIST-owner emails and
such that you might not want. If your list is not associated with a
savannah group that you are an admin of, its ok to leave it blank. But
otherwise, we recommend keeping that field populated and filtering out
automated messages you don't like, so that we can contact you directly
if needed, reset passwords, etc.

A small amount of discussion lists have some nondefault and generally
not recommended settings that don't work with sending unmodified
messages, so those got from munging turned on and will be left
alone. These settings are reply_goes_to_list, from_is_list,
anonymous_list, first_strip_reply_to, and reply_to_address.

We figured out some edge cases and how to deal with them.  Some lists
have whats called content filtering settings, most notably to convert
html only email to plain text. This means modifying the message, and we
think the best action is to munge the from just when that happens and
the message is sent from a strict DMARC domain. Mailman doesn't have
that logic yet, but we configured Exim to do it, and documented it in
part 2 of
https://wiki.list.org/DOC/What%20can%20I%20do%20about%20members%20being%20unsubscribed%20by%20bounces%20of%20Yahoo%20user's%20posts%20for%20DMARC%20policy%20reasons.
 This
also takes care of a rare case of some misconfigured mail servers which
send misconfigured or invalid DKIM signatures. Both these kinds of
messages are rare, but send out about half a million messages per day,
so its important that we fix all cases. We figured out how to do this
and documented it and we hope other mailing list administrators will use
benefit from it.

I don't think I mentioned before, but we will be running a cronjob to
check for and correct bad DMARC related list settings.

-- 
Ian Kelling | Senior Systems Administrator, Free Software Foundation
GPG Key: B125 F60B 7B28 7FF6 A2B7  DF8F 170A F0E2 9542 95DF
https://fsf.org | https://gnu.org