Invalid DKIM signatures in this list

[RW]

On Mon, 26 Nov 2018 17:10:27 +0100 (CET)
Trond Endrestøl wrote:

> 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.

That's legitimate, it signs the absence of that header if it's not
present at the time of signing.