Within the past couple of months, Xfinity changed many of their URLs. Maybe this is just now affecting your account. Could you: (A) Purge Firefox's web content cache to remove possibly conflicting files. See: [[How to clear the Firefox cache]] (only select Cached web content, don't clear all cookies and site data) If you have a large hard drive, this might take a few minutes. (B) Try using one of these URLs to access your Xfinity mail ''Direct email link:'' https://xfinityconnect.email.comcast.net/ ''New hub page:'' https://www.xfinity.com/hub/ -- toward the upper right, there's an account button (looks like a little head and shoulders in a circle) that opens a panel to sign in. Any luck using the "Check Email" link on that account panel? If those don't work either, could you copy/paste the error message you're getting in a new reply here in this thread (not by email)? Thanks.