claws-mail from openSUSE:Backports:SLE-15-SP4:FactoryFork project
Select Your Operating System
Add repository and install manually
For standard run the following as root:
zypper addrepo https://download.opensuse.org/repositories/openSUSE:Backports:SLE-15-SP4:FactoryFork/standard/openSUSE:Backports:SLE-15-SP4:FactoryFork.repo zypper refresh zypper install claws-mail