I downloaded and setup 2 days ago the Mozilla Thunderbird email program. My gmail account did fine and it operates as normal. My Comcast account does not even though when I set it up I got the green check mark and Comcast was recognized and registered. Now I constantly get this message: Login to server Mail.comcast.net with username ( withheld ) failed. I don't know how much more I can do that what I have already done? The Thunderbird program recognizes Comcast and Google granted access to my account. How can I stop this frequent fail message?