There is no UI to do it yet, however you can already configure alert email notifications with an API call. Refer to the module’s README for details.
For example:
api-cli run module/metrics1/configure-module --data '{"prometheus_path": "", "grafana_path": "", "mail_to": ["me@nethserver.org"], "mail_from": "no-reply@nethserver.org", "mail_template": ""}'