Send user email through rest services
To add informations to the view, which are not displaying of whatever reasons - you can hook into the view and "print" the informations manually.

Step 1 Create a custom module
(https://www.drupal.org/docs/8/creating-custom-modules)
I'm not sure, but probably you can add the preprocess in the MYTHEME.theme-File. Then you do not need your own module for this.

Step 2 Add the preprocess hook (https://api.drupal.org/api/drupal/core%21modules%21views%21views.theme.inc/function/template_preprocess_views_view/8.5.x)

MYMODULE_preprocess_view(&amp;$variables) {
    // Todo: check if the view is the view you want to add the user email.
    $user_id = 1; // Change for other users.
    $user = Drupal::entityTypeManager()-&gt;getStorage('user')-&gt;load($user_id);
    $variables['users'][$user_id] = $user;
}


Step 3 In the twig-template of the view you can add the userdata (https://api.drupal.org/api/drupal/core%21modules%21views%21views.theme.inc/group/views_templates/8.5.x)

{{ dump(users) }}     {# for the user array. #}
{{ dump(users[1]) }}  {# for the user with the id 1 #}