iCloud server blocking email from legitimate senders

This issue was raised in 2014 and iCloud does not seem too hav offered any solution. To copy the original complaint (which is the same for me) :

Over the past few weeks, I've noticed several legitimate emails blocked from my iCloud account. Not delivered as junk, but completely filtered from reaching my inbox. These were all sent from known contacts (some flagged as VIP). The only reason I knew they were sent was because I either saw an alert pop up in notification center or the sender contacted me. At this point, I don't even want to think about the volume of messages blocked that I simply never knew existed.

After contacting iCloud Support a few times, I have yet to receive an acceptable answer. I understand the need for server-level spam control, but Apple clearly hasn't gotten it right yet. In the meantime, why not deliver flagged and let the user determine validity?

I'm not thrilled about it, but I'm going to have to move back to Gmail. At least I'll actually get all of my mail.

Has anyone gotten a real answer from Apple or have a different take on this?