I've adjusted my DKIM verifier so that it fails if a message contains more than one of any of these headers:
From Sender Subject Date To Cc MIME-Version Content-Type Content-Transfer-Encoding It doesn't check whether they're signed, just counts the headers. I'll let you know if anything awful hap NO CARRIER _______________________________________________ NOTE WELL: This list operates according to http://mipassoc.org/dkim/ietf-list-rules.html