This container can be pulled via:
  docker pull registry.opensuse.org/opensuse/factory/zsystems/totest/containers/opensuse/dovecot:2.3
  docker pull registry.opensuse.org/opensuse/factory/zsystems/totest/containers/opensuse/dovecot:2.3-7.78
  docker pull registry.opensuse.org/opensuse/factory/zsystems/totest/containers/opensuse/dovecot:latest

Set DOCKER_CONTENT_TRUST=1 to enable image tag verification.