When you are using your Comcast email account, but
Comcast email account is not working at the moment. So no need to take tension, there are many possible reasons like your slow internet issue, and when you enter an incorrect username or password. If you want to solve this problem by yourself, you have to clear your browser history and again
login to your Comcast email account.
See also -
https://getassist.net/fix-comcast-email-login-errors/