Email blacklist error

@XfinityPeterH​ - no transfer to Yahoo. It’s a Comcast/Xfinity email that I’m trying to access via Apple Mail app on my phone. It’s been working up until about a day or two ago. When I first signed in on the web browser, I could see all of my emails that I would expect to see coming in as new. I did not open any of them or delete them, and when I re-logged back in, they were no longer there and I’m no longer receiving emails in either the web browser or through the app. Actually, I’m receiving a few, but maybe ten received out of 50 that there there. I’ve been sent several emails today that I’m expecting and in need of and I can’t access.

Thank you for confirming that it is a Comcast email that you are trying to access @user_v3roif via the Apple Mail app. We are migrating all Comcast email address to Yahoo Mail but you will be retaining your existing email address. This is happening in phases though so we're just trying to determine if your being affected by the transition or not. To confirm, have you received a 30-day notice email regarding this change yet? May I also confirm if you are experiencing any issues with any other apps? And, what web browser are you using to try to access your emails? Have you tried an alternate browser?