Someone posited:
Or it's the DKIM thing again.
YES!! IT'S THE DKIM "THING" AGAIN. STOP GUESSING.
I have a Great ISP -- who does Fantastic spam filtering. The Trinity list emails all go into the Spam folder -- because of DKIM failure. https://www.google.com/search?q=dkim+spf
Or, they normally would... Except, I am able to insert _my_ email filters in ahead of any filtering by my ISP. And, thus I can direct these emails to a folder of my choosing in spite of the DKIM failures.
Now-a-days there are many, many ISP's that flat out reject incoming email traffic if the DKIM check fails. Other ISPs call it spam (which it is most often) and shunt it to the spam folder.
Calling it "Ham" in some ISPs may only solve the problem for a short time -- until that "up vote" ages off.
Jonesy