Thunderbird 143 is out with bug fixes, bug fixes and more bug fixes. The Thunderbird 140 release brought a sizeable set of improvements, and last month’s Thunderbird 142 added a couple too (like digital signatures in PDFs). Downloads will default to monthly release builds (which as of writing, will be Thunderbird 143). Upgrading to a new Thunderbird release is easy, though it depends on which platform or packaging format is involved. For monthly release builds on Windows or macOS, updating takes place inside of Thunderbird: open Thunderbird, go to the Help menu and select About.