[Mailman-Users] cause of bounces

Grant Taylor gtaylor at tnetconsulting.net
Tue Oct 17 13:38:48 EDT 2017

On 10/17/2017 10:55 AM, Christian F Buser via Mailman-Users wrote:
> I can perfectly follow your thoughts and arguments, they appear to be 
> justified and reasonable.

Thank you.  I tried to make them so that people could understand, even 
if they choose to disagree.

> However, could you please elaborate whether Mailman (version 2.x or 
> 3.x) or any other mailing list software really follows your ideas?

Yes!!!  Mailman (and other MLMs) /can/ be configured to be SPF / DKIM / 
DMARC compliant!

> If it is just a question of the setup for the mailing list, I would 
> expect your instructions on how to set it up properly.

I don't have the exact step by step details.  -  I'm sure others 
(Mark...) on this list can give specifics on /how/ to configure Mailman.

The high level as I understand it is to do the following:

1) Set dmarc_moderation_action to munge From header.
2) Set REMOVE_DKIM_HEADERS to Yes (1) or 2 or 3.
3) Send messages from the list address.  I recommend VERP.

Doing those three things ensures that messages leaving the mailing list 
do not violate the original sending domain's SPF / DKIM / DMARC security 

I would suggest that you also consider adding SPF / DKIM / DMARC for the 
domain of the mailing list to apply similar protections to outgoing 
messages.  However that is not necessary to avoid undesired bounces.

> Thank you, Christian
You're welcome.

Grant. . . .
unix || die

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