I'm a Windows OS user but have located some info which may help you. Zorin based on Linux Ubuntu OS. This Help Article may be of assistance. * https://support.mozilla.org/en-US/kb/installing-thunderbird-linux This is a link to the release notes - scroll down to see what packages etc you will need to have got installed. * https://www.thunderbird.net/en-US/thunderbird/138.0.1/system-requirements/ This is a link to the thunderbird webpage for downloads - you would need to make sure you are downloading correct language and operating system. * https://www.thunderbird.net/en-US/thunderbird/all/