This container can be pulled via:
  docker pull registry.opensuse.org/devel/kubic/containers/container/opensuse/postfix:3.9.0
  docker pull registry.opensuse.org/devel/kubic/containers/container/opensuse/postfix:3.9.0-35.77
  docker pull registry.opensuse.org/devel/kubic/containers/container/opensuse/postfix:latest

Set DOCKER_CONTENT_TRUST=1 to enable image tag verification.