Spamcop is analyzing mail headers and fails to recognize a legitimate mail host at Rackspace. The host is: smtp4.gate.iad3a.rsapps.net
I went though the mailhost list on my mailhosts tab and it doesn't appear.
Here is a snip from the analysis:
3: Received: from [134.58.240.129] ([134.58.240.129:54407] helo=cavuit01.kulnet.kuleuven.be) by smtp4.gate.iad3a.rsapps.net (envelope-from <x>) (ecelerity 2.2.3.49 r(42060/42061)) with ESMTP id 0F/73-03583-136B9755; Thu, 11 Jun 2015 12:24:17 -0400
Hostname verified: rhcavuit01.kulnet.kuleuven.be
Possible forgery. Supposed receiving system not associated with any of your mailhosts
Will not trust this Received line.