I thought I'd change my Comcast username to something else and ended up changing my Comcast password as well, all that works now with Comcast account, so I also needed to change the info in Tbird to reflect what I changed in Comcast. Now when I send test mail Comcast receives mail, but Thunderbird shows window 'Sending of username did not succeed. Mail server mail.comcast.net responded: [AUTH] Authentication failed.' and next window to popup asks for password but for old username and I've tried all passwords possible(2) and they won't work. What did i do ? I so like using Tbird better than Comcast mail.