Comcast is blocking emails from clients and people as phishing, bounces back to them

Comcast is blocking emails from clients and people I know, saying they're rejected as "phishing."

I've been having this problem for almost a year now - off and on it seems. I've tried:

1. Disabling the Comcast spam filter and allowing all emails

2. I've disabled all the Filter Rules I had in place

3. I'm now making sure all the emails addresses are in my Xfinity Address book.

Any suggestions? Thank you for any help you can give.