view_user_email.module

<?php

/**
 * @file
 * Contains view_user_email.module.
 */

use Drupal\Core\Routing\RouteMatchInterface;
use Drupal\Core\Access\AccessResult;

/**
 * Implements hook_help().
 */
function view_user_email_help($route_name, RouteMatchInterface $route_match) {
  switch ($route_name) {
    // Main module help for the view_user_email module.
    case 'help.page.view_user_email':
      $output = '';
      $output .= '<h3>' . t('About') . '</h3>';
      $output .= '<p>' . t('Allow site administrator the ability to grant users of certain roles access to another users email address.') . '</p>';
      return $output;

    default:
  }
}

/**
 * Implements hook_entity_field_access().
 */
function view_user_email_entity_field_access($operation, \Drupal\Core\Field\FieldDefinitionInterface $field_definition, \Drupal\Core\Session\AccountInterface $account, \Drupal\Core\Field\FieldItemListInterface $items = NULL) {
  if ($field_definition->getName() != 'mail' || $operation != 'view') {
    return AccessResult::neutral();
  }
  if ($account->hasPermission('access email field')) {
    return AccessResult::allowed();
  }
  return AccessResult::neutral();
}