valid email going to spam

Over the past couple of weeks I've started receiving multiple valid emails (from various sources) in my spam folder. Even when I click on it as NOT SPAM, subsequent emails still end up there. And it is also happening in reverse. When I send a group BCC email to a number of recepients , it is  either not delivered or it ends up in their spam folder. Is Xfinity using some kind of new anti-spam filter? How can I bypass it to both send and receive valid emails?