IDN-Domain Emails - dont pass email check.
See Issue https://issues.civicrm.org/jira/browse/CRM-15975 and
Email validation is too restrictive (rejects IDN addresses) https://issues.civicrm.org/jira/browse/CRM-16313
Emails with these Characters should pass https://www.denic.de/en/know-how/idn-domains/idn-character-list/
Last tested with Civicrm 5.22.1 + Drupal 7 Php 7.2x Intl enabled.