iCloud Mail Errors

When I attempt to access iCloud mail through a web bowser, any browser. I get the attached error message. This will occur with Windows 10 (firefox, chrome, edge), Ubuntu (chrome, firefox) and MacOS Safari. I have attempted this from three other machines, on different networks. I need to access the preferences and disable a email forwarding rule but the error precedes the loading of the application.

I have accessed mail many times in the past using this method. I think this has started in the last week or two.

Thoughts?