This container can be pulled via:
  docker pull registry.opensuse.org/home/defolos/bci/cr/sle-15-sp7/containerfile/containers/postfix:3.8
  docker pull registry.opensuse.org/home/defolos/bci/cr/sle-15-sp7/containerfile/containers/postfix:3.8-17.20

Set DOCKER_CONTENT_TRUST=1 to enable image tag verification.