This container can be pulled via:
  docker pull registry.opensuse.org/home/etampl/branches/opensuse/templates/images/tumbleweed/containers/tigermail:0.2.7
  docker pull registry.opensuse.org/home/etampl/branches/opensuse/templates/images/tumbleweed/containers/tigermail:latest

Set DOCKER_CONTENT_TRUST=1 to enable image tag verification.