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I personally do not know what a DKIM Signed message is, but I do know what "text" is and I am certain that any asshole can type and or copy/paste it. Some better than others. I fail to see why a bunch of text is conclusive proof of anything. If these are real I think you should be forwarding all of this to the SEC or any other alphabet soup bureau that might be interested. Posting them here is suspicious to say the least.
part of DKIM signing is integrity verification like PGP. if something's fishy (body or sender changed, mail not really from that domain) then the sig won't match
http://9vx.org/~dho/dkim_validate.php is the first online tool i could find that checks signed mail for tampering. try it out if you like