First rule: FileZilla never does anything by itself.
I have no idea how TB stores emails exactly, but could it be you slipped while dragging and dropping? There is no Undo, you need to find the files and drag them back manually. Sorry if I cannot help you better.
I have no idea how TB stores emails exactly, but could it be you slipped while dragging and dropping? There is no Undo, you need to find the files and drag them back manually. Sorry if I cannot help you better.