The Litmus spam test is passing for all filters with flying colors except Cloudmark which is flat out failing and apparently has been for some time for a new client of mine. Unfortunately Litmus does not suggest any ways to remedy for Cloudmark like it usually does for other failing filters.

Cloudmark claims to handle 1 in 8 inboxes so while I'm not sure how much of an issue it is for this specific clients list, I'd like to investigate. I'm not sure what to do to fix it... The ESP is MailChimp. Has anyone else encountered this issue? Any ideas much appreciated!