[Mailman-Users] Prevent MM from adding a CC for DMARC munged posts?

Mark Sapiro mark at msapiro.net
Fri Jan 11 14:23:36 EST 2019

On 1/11/19 7:06 AM, David Gibbs via Mailman-Users wrote:
> Does anyone know if there is a way to prevent MM from adding the
> original posters email address as a CC when the DMARC munging is done?

The following comment from Mailman/Handlers/CookHeaders.py describes the
goals for handling the original From:

>     # MAS: We need to do some things with the original From: if we've munged
>     # it for DMARC mitigation.  We have goals for this process which are
>     # not completely compatible, so we do the best we can.  Our goals are:
>     # 1) as long as the list is not anonymous, the original From: address
>     #    should be obviously exposed, i.e. not just in a header that MUAs
>     #    don't display.
>     # 2) the original From: address should not be in a comment or display
>     #    name in the new From: because it is claimed that multiple domains
>     #    in any fields in From: are indicative of spamminess.  This means
>     #    it should be in Reply-To: or Cc:.
>     # 3) the behavior of an MUA doing a 'reply' or 'reply all' should be
>     #    consistent regardless of whether or not the From: is munged.
>     # Goal 3) implies sometimes the original From: should be in Reply-To:
>     # and sometimes in Cc:, and even so, this goal won't be achieved in
>     # all cases with all MUAs.  In cases of conflict, the above ordering of
>     # goals is priority order.

If your goal is to not expose the original From: address, you can make
the list anonymous or if you have sufficient access, modify the code.

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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