It works in Explorer because you're not asking the BT server to communicate with your computer, you're managing your mail directly through the webmail screen. If you want to use a client program like Thunderbird you have to ensure that the server settings are correct. BT explains them here: http://bt.custhelp.com/app/answers/detail/a_id/44917/~/what-are-the-settings-for-outgoing-and-incoming-bt-email-servers%3F Note that BT has particular requirements about security settings and authentication when you try to get your mail. If you don't have those settings correct, the server will not accept your login, and Thunderbird will give you an error message about your password possibly being incorrect. That's not helpful, because in many cases the password '''is''' correct: it's the security settings etc. that are not.