diff --git a/src/Mailer/Transport/MailgunTransport.php b/src/Mailer/Transport/MailgunTransport.php
index cb8b616..e85f708 100644
--- a/src/Mailer/Transport/MailgunTransport.php
+++ b/src/Mailer/Transport/MailgunTransport.php
@@ -327,4 +327,13 @@ protected function _processHeaders(Message $message): void
             }
         }
     }
+
+    /**
+     * clone
+     * @return void
+     */
+    public function __clone()
+    {
+        $this->_reset();
+    }
 }