A recent Windows update on my Dell laptop resulted in an unusable copy of Windows(thanks Microsoft). After much time and effort, Microsoft's only solution was to do a fresh install of Windows which we did. Of course all software and apps had to be reinstalled. I have used Thunderbird on this laptop for years successfully. I downloaded the most current verision of Thunderbird and installed it. I then attempted to add my email account. I entered my name, email account name, and password. Message came back, "Configuration found in Mozilla ISP database." Configuration shows Incoming: IMAP, SSL/TLS. Outgoing: SMTP, SSL/TLS. I then clicked on the "Done" box. Next an Xfinity window opens with my username. The next box says "Let's go". I clicked that box. A window pops open that says, "ACCESS DENIED, You don't have access "http://login.xfinity.com/login" on this server. I googled that line and found many responses. I tried many of the solutions shown to no avail. I then contacted Comcast/Xfinity. After hours on the phone and finally reaching Comcast Assurance Level 2, the agent and I tried various things and still to no avail. So, here I am. Anyone there have any ideas on how to proceed. Thanks to anyone who tries.