Temporarily blacklisted IP

I have been unable to get my Comcast email with the Apple Mail app on my MacBook, iPhone and iPad. When I click on the account, I get a message - "Temporarily Blacklisted IP Address-Try Again Later."

The problem started yesterday and is still continuing. I did not make any changes on my devices. I haven't done anything else that would have affected the IP address. I'm in the same location as usual, trying to log in the same way as always. 

Everything else is working fine.

1.  I can access my Comcast email on connect.xfinity.com on all three devices (Mac, iPhone and iPad). The problem is only when using Apple Mail.

2. In the Xfinity email settings, the third party access security checkbox is on.

3. I can get email from my other accounts using Apple Mail.

4. My internet is working fine. I reset the router to see and the Comcast issue is still there.

4. I've made sure that the user name and password on the Comcast accounts is correct. I've checked it multiple times.

I have not experienced this "temporarily blacklisted IP" issue before.  

I'd appreciate any suggestions. Thanks.