#2999 introduced a new pattern checker and implemented a new function within PHPMailer. This enhancement enables you to directly invoke getLastTransactionID on PHPMailer itself

src/PHPMailer.php

@@ -5249,4 +5249,14 @@ class PHPMailer
     {
         $this->oauth = $oauth;
     }
-}
+
+    
+    /**
+     * Get the last transaction ID.
+     *
+     * @return string The last transaction ID.
+     */
+    public function getLastTransactionID() {
+        return $this->smtp->getLastTransactionID();
+    }
+}

src/SMTP.php

@@ -196,6 +196,7 @@ class SMTP
         'Haraka' => '/[\d]{3} Message Queued \((.*)\)/',
         'ZoneMTA' => '/[\d]{3} Message queued as (.*)/',
         'Mailjet' => '/[\d]{3} OK queued as (.*)/',
+        'VcMailer' => '/[\d]{3} 2.0.0 OK (.*)/'
     ];
 
     /**