Subject: IETF Mail List Failure Follow Up

From: IETF Executive Director <[email-masked]>
Date: Thu, 24 May 2018 15:59:13 -0700

As previously reported, on May 17th, the outbound traffic from all
IETF list mails stopped. After the issue was repaired, members of the IETF Community requested an explanation of the nature of the problem. This message provides a summary of the
problem and the steps taken to correct it.

The cause was an incorrect configuration of the dmarc-rewrite program
that was made to activate the DMARC processing for domains with
'reject' as their policy.  The incorrect configuration was provided by
the Tools Team.  Although testing was done on five mail lists before
this was activated for all mail lists, the testing did not catch this
problem.

The incorrect configuration of the dmarc-rewrite program caused it to
bounce all outbound deliveries back to Mailman, and then Mailman
interpreted the returned messages as destination delivery bounces,
discarding them.  Since they were discarded, the Secretariat could not
automatically resend these messages for the authors.

The Secretariat temporarily disabled the dmarc-rewrite program so that
outgoing messages were flowing again.  Then, the Secretariat worked
with the Tools Team to correct the configuration of the dmarc-rewrite
program.  In less than a day, the configuration was corrected and the
DMARC processing was working properly for all mail lists.

Alexa Morris
IETF Executive Director