DKIM signed mails are not recognized when the mails got no fileextension:
DKIM-Signature: v=1; a=rsa-sha256; s=brisbane; d=example.com;
c=simple/simple; q=dns/txt; email@example.com;
h=Received : From : To : Subject : Date : Message-ID;
Received: from client1.football.example.com [192.0.2.1]
by submitserver.example.com with SUBMISSION;
Fri, 11 Jul 2003 21:01:54 -0700 (PDT)
From: Joe SixPack <firstname.lastname@example.org>
To: Suzie Q <email@example.com>
Subject: Is dinner ready?
Date: Fri, 11 Jul 2003 21:00:37 -0700 (PDT)
We lost the game. Are you hungry yet?
DKIM Spec rfc4871
message/rfc822 is only set when the file ends with .eml
The finally verified mail starts with
which might also be recognized as text/plain.
Check the related Ticket
(Could not attach the example mails, got the following error: JIRA could not attach the file as there was a missing token. Please try attaching the file again.)