[5.x] Allow conditional sending of form submission emails

src/Events/FormSendingEmails.php

@@ -0,0 +1,22 @@
+<?php
+
+namespace Statamic\Events;
+
+use Statamic\Contracts\Forms\Submission;
+
+class FormSendingEmails extends Event
+{
+    public function __construct(public Submission $submission)
+    {
+    }
+
+    /**
+     * Dispatch the event with the given arguments, and halt on first non-null listener response.
+     *
+     * @return mixed
+     */
+    public static function dispatch()
+    {
+        return event(new static(...func_get_args()), [], true);
+    }
+}

src/Http/Controllers/FormController.php

@@ -7,6 +7,7 @@
 use Illuminate\Support\MessageBag;
 use Illuminate\Validation\ValidationException;
 use Statamic\Contracts\Forms\Submission;
+use Statamic\Events\FormSendingEmails;
 use Statamic\Events\FormSubmitted;
 use Statamic\Events\SubmissionCreated;
 use Statamic\Exceptions\SilentFormFailureException;
@@ -83,7 +84,7 @@ public function submit(FrontendFormRequest $request, $form)
             SubmissionCreated::dispatch($submission);
         }
 
-        SendEmails::dispatch($submission, $site);
+        SendEmails::dispatchUnless(FormSendingEmails::dispatch($submission) === false, $submission, $site);
 
         return $this->formSuccess($params, $submission);
     }