yii\mail\MessageInterface::getTo PHP Method

    public function getTo();

 /**
  * Will write log to database
  * @param boolean $result
  * @param MessageInterface $message
  */
 public function createLog($result, $message)
 {
     $mail = new Mail();
     $mail->estado = $result ? Mail::IS_SENT : Mail::IS_NOT_SENT;
     $mail->created_at = time();
     $mail->controller = \Yii::$app->controller->id;
     $mail->action = \Yii::$app->controller->action->id;
     $temp = [];
     //store emails as string
     foreach ($message->getTo() as $email => $name) {
         $temp[] = $email;
     }
     $mail->emails = implode(', ', $temp);
     $mail->body = $message->toString();
     $mail->save();
 }