O Mozilla Thunderbird is a free software application for monitoring your email or RSS feeds that interest you. The application is available on Microsoft operating systems Windows, Apple Macintosh and Linux.
It was developed by the Mozilla Foundation and the first version was released on December 7, 2004. The first 1.000.000 downloads were made within 10 days of the first release. By 2007, the app had been downloaded 50.000.000 times.
A new version of it was released today email client Thunderbird. Thunderbird version 78.2.0 is an update to the stable version of Thunderbird 78.0.
Thunderbird 78.0 is available for download from the project website and only supports MailExtensions and not the classic add-ons that supported older versions. So there is a possibility that some add-ons will no longer work in the new large version.
If you are already using Thunderbird 78.x you can check for help from the Help - About Thunderbird path.
All the rest you are interested in the email client can be downloaded on the platform you needed from official webpage.