[Mailman-Users] Unsubscriptions after DMARC fix

Lindsay Haisley fmouse at fmp.com
Mon Apr 3 13:28:09 EDT 2017

Last month a Mailman (v2.1.18-1) list on my server got hit with a bunch
of bounces based on DMARC rejections from Gmail, Yahoo and Hotmail
which honor "p=reject" in a DMARC record. The list had not previously
been configured to handle DMARC issues so at that time I
set dmarc_moderation_action to "Munge From" which I assumed would solve
the problem going forward.

Bounce processing for the list is set to send 10 probe messages at 3
day intervals, and last night all of these addresses were unsubscribed.
It seems that probe messages to these addresses, which I believe come
from the list server's mailman address, were also bouncing. I would
assume that messages which come directly from our server and are not
reflected through a redirection or mailing list wouldn't be subject to
rejection based on DMARC policy.

Why would this be? What can be done to address the problem?

Lindsay Haisley       | "The first casualty when
FMP Computer Services |         war comes is truth."
512-259-1190          |            
http://www.fmp.com    |     -- Hiram W Johnson

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