Hi there! My name is***** am a computer professional with over 15 years of experience with both Mac and Windows computers, phones, tablets, and printers. It would be my pleasure to assist you with this. I use Thunderbird myself. Would you be willing to allow me to connect to your computer to work on this while you watch, at no additional charge? You may see an offer for additional services but you can just ignore those, they are automated.
If you'd like for me to connect to your computer to fix this please click this link:
On the page that opens up, click "I Agree."
Download the remote file when prompted, and then OPEN/RUN the "Elsinore Screen Connect" file downloaded (at the very bottom of your browser window, usually in the left corner.)
I'll then be connected.
Please let me know if you have any problems.