Struggling to get OpenARC working with Mailman 3

[Philip Colmer <philip.colmer@xxxxxxxxxx>]

I've set up an Ubuntu 20.04 server with Postfix, OpenDKIM, OpenARC and
Mailman 3.

In a simple test of sending email directly from the server to an
external mailbox, both DKIM and ARC appear to be working:

Delivered-To: philip.colmer@xxxxxxxxxxxxxx
Received-SPF: pass (zohomail.com: domain of mm3.lavasoftware.org
designates 3.230.84.86 as permitted sender) client-ip=3.230.84.86;
envelope-from=philip.colmer@xxxxxxxxxxxxxxxxxxxx;
helo=mm3.lavasoftware.org;
Authentication-Results: mx.zohomail.com;
dkim=pass;
spf=pass (zohomail.com: domain of mm3.lavasoftware.org designates
3.230.84.86 as permitted sender)
smtp.mailfrom=philip.colmer@xxxxxxxxxxxxxxxxxxxx;
arc=pass (i=1 dmarc=pass fromdomain=mm3.lavasoftware.org)
ARC-Seal: i=2; a=rsa-sha256; t=1631777446; cv=pass;
d=zohomail.com; s=zohoarc;
b=Sf9f7Vc4utokJHB/AhzIBiYUQABBaJmLA5x/oY3fq5yPXxuAW+a5qed5oCPJEHzwopQXN8u/4hzxFa3+8sXJC5tIYMiuG4dr9EyW+oxSMz6vveiiybchxVGMqw/i9gPT5CWT4Q6eHMdiu/3AsBXdwTBqHZy61y6OACk4BbpI8FA=
ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed;
d=zohomail.com; s=zohoarc;
t=1631777446; h=Date:From:Message-ID:Subject:To;
bh=47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU=;
b=BDNvyCqYEUnD61N5OAtR3W/67HOciIm0eLZdMB4aiigaRO8rlalyM5u5Y41ADg5GJl5gyE9LgkQxpGhQfDlTAD7NvEjsh/LGElk+Esxcf7LFxhRDc9i4MqZvgXu30boDquKFQrSJVZPlpoCY3wOLkKa0F6PKz9hKGLvx8OxweOk=
ARC-Authentication-Results: i=2; mx.zohomail.com;
dkim=pass;
spf=pass (zohomail.com: domain of mm3.lavasoftware.org designates
3.230.84.86 as permitted sender)
smtp.mailfrom=philip.colmer@xxxxxxxxxxxxxxxxxxxx;
arc=pass (i=1 dmarc=pass fromdomain=mm3.lavasoftware.org)
Return-Path: <philip.colmer@xxxxxxxxxxxxxxxxxxxx>
Received: from mm3.lavasoftware.org (mm3.lavasoftware.org
[3.230.84.86]) by mx.zohomail.com
with SMTPS id 1631777446561547.6433787962904; Thu, 16 Sep 2021
00:30:46 -0700 (PDT)
Received: by mm3.lavasoftware.org (Postfix, from userid 1000)
id 11CC0BE198; Thu, 16 Sep 2021 07:30:45 +0000 (UTC)
ARC-Seal: i=1; a=rsa-sha256; d=mm3.lavasoftware.org; s=mailman; t=1631777445;
cv=none; b=ld42BgcROQcdXFNd9MorNvDrjS/EDoFKRFfCJBolfRF3Cg093kCAD8/3lIf5E7v8/9I/qePgswN9BgLbbqxr1WvIlJBZP7aBdULMZ5NlfGDuR7q3TA14hWaaS2AFsYp6rVDPSuyBl8Nl86zHfWvNDsg8ZVkDQSDvy+2BMKKRkFY=
ARC-Message-Signature: i=1; a=rsa-sha256; d=mm3.lavasoftware.org; s=mailman;
t=1631777445; c=relaxed/relaxed;
bh=47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU=;
h=DKIM-Signature:To:Subject:X-Mailer:Message-Id:Date:From;
b=SpnEUbFx9bzXUUvWy3symoTeZlDzDPhfcoPVsvHN1zlh3alvvADoi2/UUTRF0l+bX6Iagtgn8eswO9x4Z5YnJtak3bYqd2p59xf9oMswiUvR0piY4sVx3WEE5rqQMibRJrzBmQqTan2xsmOxpCmWSgbv2o+yI+CYg++5pXEDjC4=
ARC-Authentication-Results: i=1; mm3.lavasoftware.org
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
d=mm3.lavasoftware.org; s=mailman; t=1631777445;
bh=47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU=;
h=To:Subject:Date:From:From;
b=VizzJTtzye+R1HGgm7JcpB/a/KqImAjxyDLUvLucTLiquO0xjwD1HCR6N8UXDpV5t
nwNULTm0DhjyBrbZMs7jP0hTyS92PXOsIela2IypJUV3KGCagi4+ax6THHlkMgHNv3
zNnTDhTjJPUyGHKwBu9g4vT0SRaVV4VFuQGuBSBw=
To: <philip.colmer@xxxxxxxxxxxxxx>
Subject: Testing
X-Mailer: mail (GNU Mailutils 3.7)
Message-Id: <20210916073045.11CC0BE198@xxxxxxxxxxxxxxxxxxxx>
Date: Thu, 16 Sep 2021 07:30:45 +0000 (UTC)
From: Ubuntu <philip.colmer@xxxxxxxxxxxxxxxxxxxx>
X-ZohoMail-DKIM: pass (identity @mm3.lavasoftware.org)
X-ZohoMail-Owner:
<20210916073045.11CC0BE198@xxxxxxxxxxxxxxxxxxxx>+zmo_0_philip.colmer@xxxxxxxxxxxxxxxxxxxx

However, if the email is sent to a Mailman list and Mailman then sends
the email on, the headers are no longer valid:

Delivered-To: philip.colmer@xxxxxxxxxxxxxx
Received-SPF: pass (zohomail.com: domain of mm3.lavasoftware.org
designates 3.230.84.86 as permitted sender) client-ip=3.230.84.86;
envelope-from=test-bounces+philip.colmer=codelinaro.org@xxxxxxxxxxxxxxxxxxxx;
helo=mm3.lavasoftware.org;
Authentication-Results: mx.zohomail.com;
dkim=pass;
spf=pass (zohomail.com: domain of mm3.lavasoftware.org designates
3.230.84.86 as permitted sender)
smtp.mailfrom=test-bounces+philip.colmer=codelinaro.org@xxxxxxxxxxxxxxxxxxxx;
arc=fail (Bad Signature)
Return-Path: <test-bounces+philip.colmer=codelinaro.org@xxxxxxxxxxxxxxxxxxxx>
Received: from mm3.lavasoftware.org (mm3.lavasoftware.org
[3.230.84.86]) by mx.zohomail.com
with SMTPS id 1631778422868332.996514603768; Thu, 16 Sep 2021 00:47:02
-0700 (PDT)
Received: from ip-172-31-73-169.ec2.internal (localhost [127.0.0.1])
by mm3.lavasoftware.org (Postfix) with ESMTP id A710EBDF0B
for <philip.colmer@xxxxxxxxxxxxxx>; Thu, 16 Sep 2021 07:47:01 +0000 (UTC)
Received: by mm3.lavasoftware.org (Postfix, from userid 1001)
id B116FBE198; Thu, 16 Sep 2021 07:46:59 +0000 (UTC)
ARC-Seal: i=2; a=rsa-sha256; d=mm3.lavasoftware.org; s=mailman; t=1631778421;
cv=none; b=Yj1zJeE+QqxFKwCi6Bmr4kGpoEAF3blzJEnimK/whxz9TJUQEzfTMTHV4i+ENdF79Bm++wJTSBfASZGxtLYWLjuf1WwIgs/CPmJI5vFLFpVvPIlCPzoUcKpZ2rPpanbI1w1ZD5R9L5TYqLKk2X0LBX8h+2m2lX12QPqTnDM/omI=
ARC-Message-Signature: i=2; a=rsa-sha256; d=mm3.lavasoftware.org; s=mailman;
t=1631778421; c=relaxed/relaxed;
bh=7okxo56bDMUeGIn5d8B+1XloabAmDiswrokeAElWGvo=;
h=DKIM-Signature:ARC-Message-Signature:ARC-Authentication-Results:
Received:To:X-Mailer:Message-Id:Date:Message-ID-Hash:
X-Message-ID-Hash:X-MailFrom:X-Mailman-Rule-Misses:
X-Mailman-Version:Precedence:Subject:List-Id:Archived-At:
List-Archive:List-Help:List-Owner:List-Post:List-Subscribe:
List-Unsubscribe:From:Reply-To:MIME-Version:Content-Type:
Content-Transfer-Encoding;
b=nhhYvCuj3zPh1mEVm6BOlhNeekhBeKb2l9SIMRqZqGp8VYG6xYt8754K8qjULqn2r92Vzux1lFXqnaT0ezdGI3CADLN9jgB6NVZzZYZBigh3yAtNWlr4aT6m0wSDVUxfJbAaYFXDVLuDmzTEJfEWqPAzNmHOl7rXVqBN5FvMeow=
ARC-Authentication-Results: i=2; mm3.lavasoftware.org
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
d=mm3.lavasoftware.org; s=mailman; t=1631778421;
bh=7okxo56bDMUeGIn5d8B+1XloabAmDiswrokeAElWGvo=;
h=To:Date:Subject:List-Id:List-Archive:List-Help:List-Owner:
List-Post:List-Subscribe:List-Unsubscribe:From:Reply-To:From;
b=mLPHnhHmIOkzYTVq3NqBQepuvzC/Df3lKTYZCaB1bmpQ6PeOOz5g98HzbVVlpX9uw
afblicz/ISDs131pgU1qvHQBzWq6lKQmMSwrJzZ49CCBeksfxA9tIq4mNv4DUu09io
bMk/0uAgDSXs63mAXy6qw/JvXVTDgYMv00yZ+U2U=
ARC-Seal: i=1; a=rsa-sha256; d=mm3.lavasoftware.org; s=mailman; t=1631778419;
cv=none; b=SiDr6n4UWUHhjTPhxl06MHsElI9ZUTD8B7qLcGf1Kdfbek6OIbPt+DapUSRkRD20bKQXeCdh5O5RdhIZPOZYvYAOclMlOtyfJb5hKNTqO5hXrnVqJ0fiRMgbjQHIM2LKP4qfYVLMXkYHR7U8hNPuw2PqapiXgK8oSddP8JNMKVE=
ARC-Message-Signature: i=1; a=rsa-sha256; d=mm3.lavasoftware.org; s=mailman;
t=1631778419; c=relaxed/relaxed;
bh=tm5RPPTfV2Opc+Qi0lNHW09jqu2Otv/5tnp8ODwYPGM=;
h=To:Subject:X-Mailer:Message-Id:Date:From;
b=QnXpv4s3JciqcxnUUoumLz3GrXOh20fXnyCprPzXm5mILfC5hCLhe8sCX7CQxbsl/gRDpvQuS0DpxezG3rdvtc7yofsJ+K/oPOMHFAjjNccvmF3MUTEdPrJ8S0qNU6AWl2ApT96fi2ZtgFsJeX2dcmhExpbOWhw6p5Ap/o1gbSA=
ARC-Authentication-Results: i=1; mm3.lavasoftware.org
To: <test@xxxxxxxxxxxxxxxxxxxx>
X-Mailer: mail (GNU Mailutils 3.7)
Message-Id: <20210916074659.B116FBE198@xxxxxxxxxxxxxxxxxxxx>
Date: Thu, 16 Sep 2021 07:46:59 +0000 (UTC)
Message-ID-Hash: XBBXTI6IJ6NHUBSN5LLI7DNXWE6IOFZI
X-Message-ID-Hash: XBBXTI6IJ6NHUBSN5LLI7DNXWE6IOFZI
X-MailFrom: pjctest@xxxxxxxxxxxxxxxxxxxxxx
X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved;
emergency; loop; banned-address; member-moderation;
nonmember-moderation; administrivia; implicit-dest; max-recipients;
max-size; news-moderation; no-subject; digests; suspicious-header
X-Mailman-Version: 3.3.4
Precedence: list
Subject: [Test] Direct test
List-Id: <test.mm3.lavasoftware.org>
Archived-At: <>
List-Archive: <>
List-Help: <mailto:test-request@xxxxxxxxxxxxxxxxxxxx?subject=help>
List-Owner: <mailto:test-owner@xxxxxxxxxxxxxxxxxxxx>
List-Post: <mailto:test@xxxxxxxxxxxxxxxxxxxx>
List-Subscribe: <mailto:test-join@xxxxxxxxxxxxxxxxxxxx>
List-Unsubscribe: <mailto:test-leave@xxxxxxxxxxxxxxxxxxxx>
From: pjctest--- via Test <test@xxxxxxxxxxxxxxxxxxxx>
Reply-To: pjctest@xxxxxxxxxxxxxxxxxxxxxx
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
X-ZohoMail-DKIM: pass (identity @mm3.lavasoftware.org)

I'm struggling to understand what is going wrong with my setup.

Thanks.

Regards

Philip