Hi, Florian Weimer wrote: > * Todd Zullinger: > >> On the users list we enabled Mailman's DMARC mitigations >> several months ago. That has allowed posts from users >> @yahoo and other domains with strict DMARC settings to reach >> list subscribers @gmail and other domains which honor those >> DMARC settings. >> >> It may be worthwhile to enable those Mailman mitigations for >> all project lists by default (allowing lists who may not >> want it to disable the settings). > > Can we at least opt out as recipients, for those of us who still > exercise some control over their email infrastructure?
AFAIK, there's no individual subscriber control in Mailman.
It's applied to the list. (I'm nowhere close to an expert
with Mailman3 though, so corrections are welcome.)
However, it only affects messages from domains which have a
DMARC 'reject' policy, as configured on the users list.
So anyone with some control over their email infrastructure
shouldn't generally be affected (or will have the ability to
make adjustsments to their DMARC policy to allow mail to be
resent from the Fedora lists).
For the benefit of those who aren't familiar with Mailman's
DMARC mitigations, here's how this works on the users list:
When mailman is sending a message it checks the DMARC policy
of the sender's domain. If that policy is set to 'reject'
then Mailman will adjust the From: field to send the message
from the list address instead of the sender's.
For example, if a subscriber 'someu...@example.com' sends a
message to the list and 'example.com' has a DMARC 'reject'
policy, the original from header would be:
From: Some User <someu...@example.com>
Mailman will change that to:
From: Some User via users <us...@lists.fedoraproject.org>
It will store the original From header (I believe in
Original-From: but it's early in the day and that's from
memory, so it could be slightly off).
The advantage is that domains like @gmail.com which block
(or mark messages as spam) from domains like @yahoo.com will
no longer do so because the list has not resent mail from
@yahoo.com counter to @yahoo.com's DMARC policy.
The disadvantage is that the From: field is munged.
Overall, I think it's been an improvement on the users list.
--
Todd
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Process and Procedure are the last hiding place of people without the
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