Thank you for the details of the issue you are experiencing with your iCloud email account. I recommend reviewing the section titled "If you can't receive mail in OS X Mail" in the following article for the issue you described:
Thank you for using Apple Support Communities.
There is a known issue with iCloud where they block legitate email from arriving. I assume they do becasue iCloud lacks aduquate spam protection. You can read more here: https://www.thexyz.com/forum/viewtopic.php?f=71&t=2095