[Mailman-Users] AOL rejecting connections from mailman servers for DMARC Munging.

Mark Sapiro mark at msapiro.net
Wed Aug 24 17:30:15 EDT 2016

On 08/24/2016 12:24 PM, Ted Hatfield wrote:
> I'm running mailman version 2.1.22.
> reply_goes_to_list is set to poster
> from_is_list is set to "Munge From".
> Documentation describes "Munge From" to be
> "This action replaces the poster's address in the From: header with the
> list's posting address and adds the poster's address to the addresses in
> the original Reply-To: header."
> This means that messages with a munged From: header should pass dmarc
> checks but the senders address will be added to the reply-to header. 
> Does this not mean that the Reply-To: and the To: address will be the
> same for some users?

Well, depending on how the user crafts the post, many things are
possible, but with from_is_list = Munge from[1] and the usual situation,
the post is

From: Joe Sender <sender at example.net>
To: A list <list at example.com>

and after munging the delivered post is

From: Joe Sender on behalf of a A list <list at example.com>
Reply-To: Joe Sender <sender at example.net>
To: A list <list at example.com>

Reply-To: is the sender's address <sender at example.net> and To: is the
list address <list at example.com>. These are not the same.

[1] It is recommended to set from_is_list to No and
dmarc_moderation_action to Munge from. The resultant munging will be the
same but will only be applied to messages From: a domain publishing a
DMARC policy of reject (or quarantine if
dmarc_quarantine_moderation_action is Yes).

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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