I can neither receive nor send emails via Thunderbird. I can can however access them via my ISPs web-based email interface, which is BT. When Thunderbird tries to access the server I get the message "Sending of password for account ......@.... did not succeed. Mail server responded: Server error. Please try later". As advised elsewhere here, I have checked and account settings and password are correct, I have not downloaded a more recent version of Thunderbird. The system was working perfectly up until last night. The failure started this morning. I have tried rebooting but no luck. Is there anything I can do or is the problem at the BT end?