"Not Found on Accelerator" trying to log in to email

When trying to log in to check my email, I get the message "Not Found on Accelerator" and "Description: Your request on the specified host was not found. Check the location and try again."  I have tried 6 different browsers, 2 different devices, clearing browser data in every browser, and resetting the account password.

Searching the forums shows many others have the same problem.  None of the "solutions" ATTHelp proposed here work.  There is clearly an unfixed issue with ATT's email service.

Does anyone know a workaround for this?