Can you make sure that ****@icloud.com goes straight through to Inboxes in future?
There is certainly no way any of us here could make that happen.
I don't even think Apple can ensure that happens.
Apple doesn't control the intervening mail exchangers that your messages might pass through on the way to the recipient. email is not point to point. It can propagate through various email servers attached to the internet before it arrives at the destination server. All of those intervening email servers could decide your message is spam and mark it as such.
The recipient's email client determines what to do if it finds X-SPAM headers in the email. You can disable trusting X-SPAM headers in Mail's Junk Preferences, "Trust Junk mail headers in messages."