Invalid DKIM signatures in this list

[Trond Endrestøl]

On Mon, 26 Nov 2018 19:52+0700, Victor Sudakov wrote:

> Dear Colleagues,
> 
> I have noticed that the Mailman which manages this list keeps the sender's
> "DKIM-Signature:" header intact but modifies the body of the message by adding
> a footer.

Are you sure?

When I received your message, the hash was made up using Message-ID, 
Subject, To, From, Date, and In-Reply-To. I failed to find the latter 
field.

DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sibptus.ru;
 s=20181118; h=Message-ID:Subject:To:From:Date:In-Reply-To;
 bh=lVqWu5A0dAGlwfZYAoaU7QQKfWUKOcE/0wgIPuvq06E=; b=oSl0oX15pzIzynwTUSwgm7sFrQ
 9MJS9pRl3koZMQRB711V15zyprv+L4UHLfo/zD/iw211sA8weBVito1fZqHekD/VlMb78reY4xSfW
 UNLY9HH1RP+/pz8gORfMw7OmkB22I7i+Nxspbae5xEExcPr8YIxzhk4nqC+OdGjjQoVE=;

> This behavior invalidates the sender's digital signature with
> "dkim=fail (body hash mismatch; body probably modified in transit)". 
> I think, according to the common sense and RFC6377, the Mailman should either
> remove the "DKIM-Signature:" when modifying the body, or refrain from
> modifying the body, or add its own valid "DKIM-Signature:" from scratch. What
> is currently happening does not make sense.
> 
> Whom do I contact about it?
> 
> An example of this behaviour can be seen in the message with Message-Id:
> <20181126081310.026376ddcaad286971909626 at sohara.org> and others.

-- 
Trond.