[RndTbl] Gmail spam filtering super-aggressive lately

[Trevor Cordes]

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.