When you get an error message it useful to state all the error message word for word OR post an image of it. Often those error messages are sent by the server so any info helps to detect what it is talking about. ''re : I was told the problem is on your end.'' Who said that ? Did they tell you what the Alert 1014 meant ? Please logon to your webmail account via a browser and check to see if third party access is enabled - it must be enabled. * https://www.xfinity.com/support/articles/third-party-email-access Then post this information: In Thunderbird * Help > Troubleshooting Information * scroll down to 'Mail and News Accounts' * Copy all the data and paste it into this forum question. Then we can check you have correct server settings. By any chance - Have you recently logged onto webmail account via a browser and changed your password ?