I've configured a Mailman 3 server with Postfix and added OpenDKIM to the latter to provide the DKIM headers, and configured Mailman to provide the ARC headers.
However, in sending test messages to a mailbox hosted by Microsoft, I'm seeing a header like this:
ARC-Authentication-Results: i=2; mx.microsoft.com 1; spf=pass (sender ip is 1.2.3.4) smtp.rcpttodomain=destination.org smtp.mailfrom=mmserver.org; dmarc=bestguesspass action=none header.from=mmserver.org; dkim=test (signature was verified) header.d=mmserver.org; dkim=fail (signature did not verify) header.d=sender.org; arc=fail (47)
(I've changed the domains and IP address)
Manually sending an email from the server to the same external email address does give me an email with a valid DKIM header:
Authentication-Results: spf=pass (sender IP is 1.2.3.4) smtp.mailfrom=mmserver.org; destination.org; dkim=test (signature was verified) header.d=mmserver.org;destination.org; dmarc=bestguesspass action=none header.from=mmserver.org;compauth=pass reason=109
So I'm unclear as to where the problem may lie ...
Hence the question: does anyone have Mailman 3 + Postfix working successfully with DKIM and ARC?
Thanks.
Philip