Hello there Debbie. We have read your message. We try to help you. Oké, to what version of Thunderbird software did you update? Did you used a automatic one? Can you send me a pic or screenshot of it? https://support.mozilla.org/en-US/kb/how-do-i-create-screenshot-my-problem Try to follow the steps that are in the documentary I did send you. https://support.mozilla.org/en-US/kb/cannot-send-messages If trying after that ,but there is no result and you cannot send, then you can message me back? Greetings Firefox volunteer.