$message_cachedir has been renamed to $message_cache_dir: https://neomutt.org/guide/reference.html#3-244-%C2%A0message_cache_dir
According to: https://neomutt.org/guide/reference.html#3-380-%C2%A0realname https://neomutt.org/guide/reference.html#3-480-%C2%A0spoolfile