Hello theredianne6. We have read your message. We try to help you. https://support.mozilla.org/en-US/kb/cannot-send-messages The current configured Smtp settings have been lost. Maybe after an update the desired for Thunderbird was not achieved. And has now been filled in with different values. Put it back in order for it to function properly and you can email again online with Thunderbird as soon as this has been changed. If it says that port 25 is used, change it to 587. Port 25 is no longer a usable port number, only use it when you really need it. Port 2525 was also the successor to the previous one of port 25. Port 587 is currently in use and is current. Greetings Firefox volunteer.