[Mailman-Users] DMARC issue with Mailman List

Mark Sapiro mark at msapiro.net
Thu Mar 16 13:08:11 EDT 2017

On 03/16/2017 06:20 AM, Terry Lund wrote:
> We are getting the following error for one of our users in one of our
> mailman lists. I've tried to figure out if one of the configuration options
> in Privacy Rules can be used to address this issue, but I am afraid I am
> not real clear on the implications of the relevent DMARC related
> parameters. Any insight or assistance would be much appreciated.
> Our configuration is that our web site integration with PayPal has PayPal
> sending confirmation emails to a mailman list called treasurer-alias, so
> that multiple people are aware of the PayPal transaction.

PayPal.com publishes DMARC p=reject. Your treasurer-alias list makes
some message transformation such as adding a footer or subject prefix
that breaks PayPal's DKIM signature. Therefore recipient list member's
ISPs that honor DMARC will reject the message.

See <https://wiki.list.org/x/17891458> items 1) and 2) for ways to deal
with this. If your Mailman is 2.1.18+, I suggest setting Privacy
options... -> Sender filters -> dmarc_moderation_action to Munge From.

Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan

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