Claws Mail (previously known as Sylpheed-Claws) is a lightweight and highly configurable email client and news reader based on the GTK+ GUI toolkit, it runs on the X Window System.
Enable snaps on Kubuntu and install claws-mail-moon127
Snaps are applications packaged with all their dependencies to run on all popular Linux distributions from a single build. They update automatically and roll back gracefully.
Snaps are discoverable and installable from the Snap Store, an app store with an audience of millions.