Fatal error: Uncaught Error: Interface "Drupal\Core\Mail\MailInterface" not found in /home/www/drupal8/test/modules/contrib/mimemail/src/Plugin/Mail/MimeMail.php:18 Stack trace: #0 {main} thrown in /home/www/drupal8/test/modules/contrib/mimemail/src/Plugin/Mail/MimeMail.php on line 18