I'm a very long time user of Thunderbird and go all the way back to Netscape Suite days. (Actually back to Mosiac days but there was no email client then). It appears Mozilla has given Thunderbird a new home to ensure its future -
https://www.techradar.com/news/mozillas-venerable-email-client-thunderbird-finds-a-new-home-to-roost
https://www.techradar.com/news/mozillas-venerable-email-client-thunderbird-finds-a-new-home-to-roost