Since Thunderbird version 78, I have a problem with spell check when answering emails. My default language is Spanish, so when answering emails written in Spanish I have no problem. But when I answer an email in English, the Spelling tab has the correct language selected, see image response_spelling_dropdown.png But when I start writing everything is highlighted like it was wrong. After many tests I've discovered that if I right click on the text and check the spelling options, actually Spanish is selected, see image response_spelling_rightclick.png So, if I manually change the pull-down of the first image, first to any other language and then back to English it then works fine (and now the right-click in the text, second image, also shows English selected). As said before, this problem started with version 78. Best regards, Florencia