You can verify the authenticity of any header that appears in the DKIM signature. That's why you see things like this in the signature: h=mime-version:from:

You can verify the authenticity of any header that appears in the DKIM signature. That's why you see things like this in the signature: h=mime-version:from:date:message-id:subject:to:x-original-sender :x-original-authentication-results:precedence:mailing-list:list-id :list-post:list-help:list-archive:list-unsubscribe:list-subscribe;