unauthorized server for my comcast.net account

Why am i getting the server says unauthorized for my comcast email account?  what can i do to get rid of that annoying pop up?

Hi Stuart, can you make a screenshot of the issue?
What version of eM Client are you currently using? When the error occurs, can you switch to the log tab in the operations window where it’s displayed and copy the content of the log and send it to me as well?

Thank you,