Add option to set the default value for 'send me a copy' restriction for anonymous users

Do we need an upgrade path for this?

RTBC for me, @jibran, wouldn't it be OK since we have a default value on the call? Although maybe an upgrade path is more reliable...

Doesn't this restriction exist for security reasons? As anonymous user, you can otherwise send out spam to arbitrary e-mail addresses through that form?

Well it is OK but imo every module should clean up after itself and set defaults on module uninstall and install. I agree the feature is complete and this will be just icing on the cake.

#7 is in Re: #5

@Berdir, sure but the comment on the setting tells you that and it isn't the default, an administrator would have to enable it?

We have protection to hide "copy" field in \Drupal\contact\MessageForm::form()

    $form['copy'] = array(
      '#type' => 'checkbox',
      '#title' => $this->t('Send yourself a copy'),
      // Do not allow anonymous users to send themselves a copy, because it can
      // be abused to spam people.
      '#access' => $user->isAuthenticated(),
    );

oh... field description should be removed

I mean that comment

+++ b/contact_storage.module
@@ -44,6 +44,12 @@ function contact_storage_form_contact_form_form_alter(&$form, FormStateInterface
+    '#description' => t('Note that this may present a way for anonymous users to spam other users.'),

this nothing about anonymous users

suppose that

I'd better add a some check to make sure that anonymous users will never get a copy message
Because you can get you site blacklisted...

Rerolled patch

Fixed paths in patch

Let's try again.. ಠ_ಠ