Since this morning I am unable to send Mail via Thunderbird. I am getting the error message: 'Sending of the message failed. The message could not be sent because connecting to Outgoing server (SMTP) securesmtp.t-online.de failed. The server may be unavailable or is refusing SMTP connections. Please verify that your Outgoing server (SMTP) settings are correct and try again' I can still receive emails and I can send emails with the same outgoing server settings from a mobile device in the same WIFI. I tried re-adding one of the accounts. This problem occurs on all my email accounts. I am working on Ubuntu 20.04 and have installed Thunderbird version 102.9.0.