On 06/16/2018 05:50 AM, Richard via CentOS wrote:
Date: Saturday, June 16, 2018 05:25:05 -0500 From: Johnny Hughes via CentOS centos@centos.org
On 06/15/2018 05:18 PM, Richard wrote:
I believe this is a DMARC issue. Yahoo, among other places, has set their dmarc records to p=reject:
dig +short txt _dmarc.yahoo.com "v=DMARC1; p=reject; pct=100; rua=mailto:dmarc_y_rua@yahoo.com;"
So, if your mail hosting provider enforces dmarc,(gmail does) and you get mail from a list that doesn't rewrite the headers, and people from places like yahoo post to the list, you'll likely get some form of warning about being being kicked off the mailing list every now and then. The frequency depends on how often people from p=reject places post, and what the settings are for bounce handling of the mailing list in question.
I believe that the current version of mailman can be configured to do the necessary header rewrites. Some lists I'm on only do the rewrites for headers of posts coming from p=reject sites (much less annoying than having them all rewritten).
This is indeed what happened. An email from yahoo.com.uk caused gmail to reject all the mails sent by that user because of the yahoo DMARC settings.
We have now set the mailing list to rewrite headers. That also has set the From: of the email to the Mailing list and not the Original Author. The author is moved to the CC: block and you can still easily see who sent it and my email client (thunderbird) still does things the same way (reply to list sends to the list, reply sends to the original author).
This should prevent the yahoo/gmail (or other dmarc) issues from happening again.
For others running mailings lists on CentOS with this issue, Red Hat has back ported the 'dmarc_moderation_action' into the current version of mailman that is used in RHEL and CentOS. You can follow the instructions here for Mailman 2 (for version 2.1.18) even though the version in CentOS is mailman-2.1.15-26.el7_4.1
we will be watching the list for the next few days to see if this change is working as expected. If it id not working for other email clients please let us know.
Great job by Brian Stinson to figure all this out :)
Thanks, Johnny Hughes
Thank you - one less list I'll get kicked off of regularly.
One note, I am seeing the author in the Reply-To: in the message headers, not in the visible Cc: as you indicate:
From: Johnny Hughes via CentOS centos@centos.org Reply-To: Johnny Hughes johnny@centos.org, CentOS mailing list centos@centos.org
so to see the address of the sender I have to either poke through the headers or initiate a reply. I don't think that this is email client specific.
RIGHT ! .. I am showing that in Thunderbird for my emails (instead of CC on the lists :D). So I thought it was CC.
So in thunderbird, you should see reply to (at least I do) when viewing the mail. For other email clients, not sure what is seen.