On 2020-03-31 Alberto Abrao wrote:
Does anyone have any idea of what should I change on my end? That's weird.
Looking at your DKIM settings in your headers, I think I spotted the problem.
Alberto's: h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references;
Mine: h=Date:From:To:Cc:Subject:In-Reply-To:References;
You are trying to protect too many headers, *especially* the ones that mailman needs to change. Also, the case on yours is not RFC (though probably doesn't matter) and many headers are duplicated (weird!) indicating a misconfiguration.
Find your DKIM settings and try shortening your protected headers to a list like mine (above). And fix the case, and duplication. Any header not listed will not count in DKIM's hash of your email.
Critically, I think you need to make sure you do NOT have "sender:" protected, as mailman will always be adding/changing that header, and that will throw off the hash and DKIM verification.
MUUG's mailman may also play with the content-*. That's why I'd stick with a very small set of headers. Spammers can't really make use of those extra headers anyhow, so they don't need to be protected.