contact.module

<?php


/**
 * @file
 */
use Drupal\Core\Form\FormStateInterface;

/**
 * Form submission handler for \Drupal\user\ProfileForm.
 *
 * Saves the contact page setting.
 */
function contact_user_profile_form_submit($form, FormStateInterface $form_state) {
    $account = $form_state->getFormObject()
        ->getEntity();
    if ($account->id() && $form_state->hasValue('contact')) {
        \Drupal::service('user.data')->set('contact', $account->id(), 'enabled', (int) $form_state->getValue('contact'));
    }
}

/**
 * Form submission handler for \Drupal\user\AccountSettingsForm.
 *
 * @see contact_form_user_admin_settings_alter()
 */
function contact_form_user_admin_settings_submit($form, FormStateInterface $form_state) {
    \Drupal::configFactory()->getEditable('contact.settings')
        ->set('user_default_enabled', $form_state->getValue('contact_default_status'))
        ->save();
}