unbound from home:crameleon:LibertaCasa:Mail project
Select Your Operating System
Add repository and install manually
For 15.4 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:crameleon:LibertaCasa:Mail/15.4/home:crameleon:LibertaCasa:Mail.repo zypper refresh zypper install unbound