ALL email sent to Cox email account delivers to SPAM/JUNK folder

For several months ALL email sent to ONE of my Cox email accounts delivers to the SPAM/JUNK folder - depending on email client used. This is NEW behavior. Prior to this behavior occurring all email was delivering normally to the subject account Inbox. Email delivers normally to Inbox in ALL other Cox email accounts. Subject account spam filtering is set to NO SPAM FILTERING in webmail settings. There are no blocked senders and no blacklists setup for the subject account. I've been 'whitelisting' 'good' email since the behavior began to absolutely NO EFFECT! ALL email still delivers to the SPAM/JUNK folder - even email sent to myself from the subject Cox email account. I can get NO HELP whatsoever from Cox phone or email tech support other than 'report the specific emails to "thisisnotspam@cox.net"'. Any help here would be truly appreciated. Thank you!