Result of first experiment - personalize turned on.
Email appears as below, but hitting reply or reply-all sends the response
directly to nico@jeremygregson, without putting the list in the cc field (I
added it manually to send this).
This might be fine for lists which we want to use as one-way dissemination,
but won't be usable for lists where we want people to be able to have a
conversation on the list eg, pelicans).
jg@gmail added to the list, to see what headers I get in gmail
N / J
From: nico--- via Selenetest
Sent: Wednesday, 9 April 2025 8:25 AM
To: nico@jeremygregson.com
Cc: selenetest@lochac.sca.org
Subject: [Selenetest] Playing with mailman headers
Background:
Some members of Lochac mailing lists are getting their incoming messages
blocked by mail hosts including Google and Outlook. This appears to be
because the mail headers identify the original sender of the email to the
list, plus the list itself, and the authentication details in those headers
match mailman, but not the original sender.
Fred@gmail sends a message to lochac-announce@lochac.sca.org
mailto:lochac-announce@lochac.sca.org , which forwards it to joe@hotmail.
Hotmail complains that the message was sent from gmail, but signed by
lochac.sca.org.
This problem is not specific to mailman or Lochac. It is detailed in the
rationale behind a relatively new protocol for authenticating emails, ARC.
https://dmarcreport.com/blog/solving-dmarcs-failures-with-mailing-lists/
Solution:
ARC isn't that mature yet. There is no option to just apt install arc and
go from there, it is still at the github distribution level of acceptance.
Mailman offers a couple of settings which might resolve the problem:
personalize and anonymous list. Changing these is quick and easy, but I
don't know if it fixes the problem, or introduces new problems.
This email has just been sent to selenetest@lochac.sca.org
mailto:selenetest@lochac.sca.org , with personalize turned on. You're
seeing it because you are a member of that mailing list - feel free to
unsubscribe. I will be looking at the mail headers, adding my gmail account
to the list, and a few other tests to see what happens. Be prepared for
spam, as you watch me test things.
Cheers,
Nico
