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From: Kent <kent@kamar.nz>
To: mlmmj@mlmmj.org
Subject: [mlmmj] Mailing Lists and DKIM signing breaking when sender DKIM policy is REJECT
Date: Mon, 8 Apr 2024 17:32:01 +1200	[thread overview]
Message-ID: <81DB5D4E-7D63-4B97-8DCB-320872DDB801@kamar.nz> (raw)

Hi All,

We run a mailing list using mlmmj on our mail server.  Recently I've had clients report that emails either aren't delivered to some recipients or end up in spam for other recipients.  This started Feb apparently.

Digging into it further, I discovered that the client in question had set up their DMARC policy to REJECT.

This meant whenever they sent an email via our mailing list, their original dkim signature, after us forwarding on, was failing. And depending on the destination mail server it was either rejected completely (eg. mac.com) or sent to spam (eg. Google.com).


I set up a Google mailing list and looked into how they handle mailing lists.  It appears they strip out all relevant authentication headers and replace the 'FROM' with:   "'Sender Name' via List Name" <listname@google.com>

And based on this I have got to the point where I've replicated this behaviour, stripping the relevant headers and replacing the 'From' with the list name.

The only thing I haven't worked out is how to insert the original senders name into the 'From' so each message at least looks like it came from someone different.


Anyone have any ideas on how I can achieve this last bit in the puzzle ?

Thanks
Kent.



I followed these instructions:  http://mlmmj.org/docs/tunables/

1) Edited 'contentheaders' to:
----
Precedence: bulk
From: List Name <listname@domain.nz>
X-Mailing-List: listname@domain.nz
List-Id: <listname@domain.nz>
List-Post: <mailto:listname@domain.nz>
List-Subscribe: <mailto:listname+subscribe@domain.nz?subject=Subscribe>
List-Unsubscribe: <mailto:listname+unsubscribe@domain.nz?subject=Unsubscribe>
----

2) Edited 'delheaders' to:
----
From:
DKIM-Signature:
X-Google-DKIM-Signature:
X-Gm-Message-State:
X-Google-Smtp-Source:
Authentication-Results:
ARC-Seal:
ARC-Message-Signature:
ARC-Authentication-Results:
-----

next             reply	other threads:[~2024-04-08  5:52 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-04-08  5:32 Kent [this message]
2024-04-08  6:23 ` [mlmmj] Mailing Lists and DKIM signing breaking when sender DKIM policy is REJECT Christof Thalhofer
2024-04-08 22:23   ` Kent
2024-04-09  7:40     ` Christof Thalhofer
2024-04-09  8:46       ` Baptiste Daroussin

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