Hello Samuel,
An effective way to ge traction on your issue is to leverage any existing relationship you may have with one of our clients as our service is largely customer managed. They will be able to raise a case with our support team and work directly with them to address this issue for our global service. However if this proves to be challenging, I can certainly take a look to see if I can assist you myself. I would recommend you send me a private message with as much details as you can provide, such as complete bounce, sender and recipient, along with the sender and date of the submission to the Cloudfeedback address.
Regards,
Ben Beaulieu
Sr Technical Support Engineer