CachetHQ/Cachet/cachethq#3102 add List-Unsubscribe header

app/Bus/Handlers/Events/MessageSending.php

@@ -0,0 +1,35 @@
+<?php
+
+/*
+ * This file is part of Cachet.
+ *
+ * (c) Alt Three Services Limited
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace CachetHQ\Cachet\Bus\Handlers\Events;
+
+/**
+ * This class is called immediately before sending a message into the mail channel.
+ *
+ * @author Graham Campbell <[email protected]>
+ * @author James Brooks <[email protected]>
+ */
+class MessageSending
+{
+    /**
+     * Handle the any actions that need storing.
+     *
+     * @param \Illuminate\Mail\Events\MessageSending $event
+     *
+     * @return void
+     */
+    public function handle($event)
+    {
+        if ($unsubscribeUrl = $event->data['unsubscribeUrl'] ?? null) {
+            $event->message->getHeaders()->addTextHeader('List-Unsubscribe', '<'.$unsubscribeUrl.'>');
+        }
+    }
+}

app/Foundation/Providers/EventServiceProvider.php

@@ -21,6 +21,9 @@ class EventServiceProvider extends ServiceProvider
      * @var array
      */
     protected $listen = [
+        'Illuminate\Mail\Events\MessageSending' => [
+            'CachetHQ\Cachet\Bus\Handlers\Events\MessageSending',
+        ],
         'CachetHQ\Cachet\Bus\Events\ActionInterface' => [
             'CachetHQ\Cachet\Bus\Handlers\Events\ActionStorageHandler',
         ],