diff --git a/src/Illuminate/Mail/Events/MessageSent.php b/src/Illuminate/Mail/Events/MessageSent.php
index c482e07383cc..493e7d4380a0 100644
--- a/src/Illuminate/Mail/Events/MessageSent.php
+++ b/src/Illuminate/Mail/Events/MessageSent.php
@@ -46,14 +46,10 @@ public function __serialize()
     {
         $hasAttachments = collect($this->message->getAttachments())->isNotEmpty();
 
-        return $hasAttachments ? [
-            'sent' => base64_encode(serialize($this->sent)),
-            'data' => base64_encode(serialize($this->data)),
-            'hasAttachments' => true,
-        ] : [
+        return [
             'sent' => $this->sent,
-            'data' => $this->data,
-            'hasAttachments' => false,
+            'data' => $hasAttachments ? base64_encode(serialize($this->data)) : $this->data,
+            'hasAttachments' => $hasAttachments,
         ];
     }
 
@@ -65,13 +61,11 @@ public function __serialize()
      */
     public function __unserialize(array $data)
     {
-        if (isset($data['hasAttachments']) && $data['hasAttachments'] === true) {
-            $this->sent = unserialize(base64_decode($data['sent']));
-            $this->data = unserialize(base64_decode($data['data']));
-        } else {
-            $this->sent = $data['sent'];
-            $this->data = $data['data'];
-        }
+        $this->sent = $data['sent'];
+
+        $this->data = (($data['hasAttachments'] ?? false) === true)
+            ? unserialize(base64_decode($data['data']))
+            : $data['data'];
     }
 
     /**
diff --git a/src/Illuminate/Mail/SentMessage.php b/src/Illuminate/Mail/SentMessage.php
index cce42dbd009f..5a2a5f6b7096 100644
--- a/src/Illuminate/Mail/SentMessage.php
+++ b/src/Illuminate/Mail/SentMessage.php
@@ -51,4 +51,32 @@ public function __call($method, $parameters)
     {
         return $this->forwardCallTo($this->sentMessage, $method, $parameters);
     }
+
+    /**
+     * Get the serializable representation of the object.
+     *
+     * @return array
+     */
+    public function __serialize()
+    {
+        $hasAttachments = collect($this->sentMessage->getOriginalMessage()->getAttachments())->isNotEmpty();
+
+        return [
+            'hasAttachments' => $hasAttachments,
+            'sentMessage' => $hasAttachments ? base64_encode(serialize($this->sentMessage)) : $this->sentMessage,
+        ];
+    }
+
+    /**
+     * Marshal the object from its serialized data.
+     *
+     * @param  array  $data
+     * @return void
+     */
+    public function __unserialize(array $data)
+    {
+        $hasAttachments = ($data['hasAttachments'] ?? false) === true;
+
+        $this->sentMessage = $hasAttachments ? unserialize(base64_decode($data['sentMessage'])) : $data['sentMessage'];
+    }
 }
diff --git a/tests/Integration/Mail/Fixtures/blank_document.pdf b/tests/Integration/Mail/Fixtures/blank_document.pdf
new file mode 100644
index 000000000000..88f49e24ccb2
Binary files /dev/null and b/tests/Integration/Mail/Fixtures/blank_document.pdf differ
diff --git a/tests/Integration/Mail/SentMessageMailTest.php b/tests/Integration/Mail/SentMessageMailTest.php
new file mode 100644
index 000000000000..18c7f728eb67
--- /dev/null
+++ b/tests/Integration/Mail/SentMessageMailTest.php
@@ -0,0 +1,78 @@
+<?php
+
+namespace Illuminate\Tests\Integration\Mail;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Notifications\Events\NotificationSent;
+use Illuminate\Notifications\Messages\MailMessage;
+use Illuminate\Notifications\Notifiable;
+use Illuminate\Notifications\Notification;
+use Illuminate\Support\Facades\Event;
+use Illuminate\Support\Facades\Schema;
+use Orchestra\Testbench\TestCase;
+
+class SentMessageMailTest extends TestCase
+{
+    public function setUp(): void
+    {
+        parent::setUp();
+
+        Schema::create('sent_message_users', function (Blueprint $table) {
+            $table->increments('id');
+        });
+    }
+
+    public function testDispatchesNotificationSent()
+    {
+        $notificationWasSent = false;
+
+        $user = SentMessageUser::create();
+
+        Event::listen(
+            NotificationSent::class,
+            function(NotificationSent $notification) use (&$notificationWasSent, $user) {
+                $notificationWasSent = true;
+                /**
+                 * Confirm that NotificationSent can be serialized/unserialized as
+                 * will happen if the listener implements ShouldQueue.
+                 */
+                /** @var NotificationSent $afterSerialization */
+                $afterSerialization = unserialize(serialize($notification));
+
+                $this->assertTrue($user->is($afterSerialization->notifiable));
+
+                $this->assertEqualsCanonicalizing($notification->notification, $afterSerialization->notification);
+        });
+
+        $user->notify(new SentMessageMailNotification());
+
+        $this->assertTrue($notificationWasSent);
+    }
+}
+
+class SentMessageUser extends Model
+{
+    use Notifiable;
+
+    public $timestamps = false;
+}
+
+
+class SentMessageMailNotification extends Notification
+{
+    public function via(): array
+    {
+        return ['mail'];
+    }
+
+    public function toMail(object $notifiable): MailMessage
+    {
+        return (new MailMessage)
+            ->line('Example notification with attachment.')
+            ->attach(__DIR__ . '/Fixtures/blank_document.pdf', [
+                'as' => 'blank_document.pdf',
+                'mime' => 'application/pdf',
+            ]);
+    }
+}