Hi list admins,

We recently made a change to our email settings for wikimedia.org (and
other WMF-owned domains) to prevent our domain name from being spoofed.

Some of the listservs on this server were configured to handle this
gracefully (a “DMARC mitigation action” of “Replace From: with list
address”). However, many listservs didn’t have this set, which was causing
emails from wikimedia.org to get bounced from this list.

We don’t think that’s what listserv owners really desired, and so we’ve
changed the settings for all of our hosted listservs in two ways. Both are
under the “DMARC Mitigations” page in List Settings:

The “DMARC mitigation action” has been set to “Replace From: with list
address”.
“DMARC Mitigate unconditionally” has been set to “yes”.

The first one has the effect of changing the “From:” address - so instead
of the list showing a sender’s email as “from” their original email
address, it will instead show the listserv’s own email address as the
“From:” field. This is really the only option available for our version of
mailman, in order to continue processing DMARC-enforced emails.

The second one applies this to all emails sent to the list, regardless of
whether or not DMARC was being enforced for that particular message. This
will make the behavior consistent for all senders, which should overall
make it less confusing and avoid questions about why some emails look
different than others.

The technical description of what sparked this change is that we (WMF) have
begun enforcing DMARC[1], with a “quarantine” policy. This has the effect
of announcing to the internet that anyone who gets an email from
wikimedia.org should check to make sure the email really was sent from us,
and if it doesn’t validate, then they should send it to spam or otherwise
keep it out of the user’s inbox. This makes it much harder to send phishing
or scam emails that spoof our domain name, but also means that listserv
software like this can’t continue to benevolently spoof the sender’s email
anymore.

Many/most large internet platforms and email senders have begun enforcing
DMARC since it was introduced. We’re making this change to bring the same
level of spoof protection to Wikimedia emails and projects.

Our change should avoid disruption to emails, but the effect of the change
will be visible to list recipients, who will start seeing a different
“From:” address from senders to this listserv. If you have any questions or
concerns, or if anything unexpected occurs, please let us know by
contacting my colleague Jesse Hathaway at [email protected].

[1] https://en.wikipedia.org/wiki/DMARC

-- 
*Eric Mill*
Group Product Manager, Safety and Security
[email protected]  |  617-314-0966
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