我无法理解这个错误（swiftmailer） . 我已经例外了25端口仍然无法理解 . 请帮我吗？

$transport = Swift_SendmailTransport::newInstance();
$mailer = \Swift_Mailer::newInstance($transport);

$message = \Swift_Message::newInstance();
$message->setSubject('Email From Our Website');
$message->setFrom(array(
    $cleanEmail => $cleanName
));
$message->setTo(array('talhagillani96@gmail.com'));
$message->setBody($cleanMessage);

$result = $mailer->send($message);

if($result > 0) {
    $app->flash('success', 'Thanks So Much! You are AWESOME!!!');
    $app->redirect('/');

} else {
    $app->flash('fail', 'So Sorry, Something Went Wrong.Try Again!');
    // log that there was an error
    $app->redirect('/contact');
}

超薄应用程序错误由于以下错误，应用程序无法运行：

详细信息类型：Swift_TransportException消息：无法启动进程[系统找不到指定的路径 . ]文件：C：\ xampp \ htdocs \ Projects \ php2015 \ vendor \ swiftmailer \ swiftmailer \ lib \ classes \ Swift \ Transport \ StreamBuffer.php行：294跟踪＃0 C：\ xampp \ htdocs \ Projects \ php2015 \ vendor \ swiftmailer \ swiftmailer \ lib \ classes \ Swift \ Transport \ StreamBuffer.php（58）：Swift_Transport_StreamBuffer - > _ establishProcessConnection（）＃1 C：\ xampp \ htdocs \ Projects \ php2015 \ vendor \ swiftmailer \ swiftmailer \ lib \ classes \ Swift \ Transport \ AbstractSmtpTransport.php（113）：Swift_Transport_StreamBuffer-> initialize（Array）＃2 C：\ xampp \ htdocs \ Projects \ php2015 \ vendor \ swiftmailer \ swiftmailer \ lib \ classes \ Swift \ Transport \ SendmailTransport.php（51）： Swift_Transport_AbstractSmtpTransport-> start（）＃3 C：\ xampp \ htdocs \ Projects \ php2015 \ vendor \ swiftmailer \ swiftmailer \ lib \ classes \ Swift \ Mailer.php（79）：Swift_Transport_SendmailTransport-> start（）＃4 C：\ xampp \ htdocs \ Projects \ php2015 \ index.php（41）：Swift_Mailer-> send（Object（Swift_Message））＃5 [内部函数]：（）＃6 C：\ xampp \ htdocs \ Projects \ php2015 \ vendor \苗条\苗条\超薄\ Route.php（468）： call_user_func_array（Object（Closure），Array）＃7 C：\ xampp \ htdocs \ Projects \ php2015 \ vendor \ slim \ slim \ Slim \ Slim.php（1357）：Slim \ Route-> dispatch（）＃8 C：\ xampp \ htdocs \ Projects \ php2015 \ vendor \ slim \ slim \ Slim \ Middleware \ Flash.php（85）：Slim \ Slim-> call（）＃9 C：\ xampp \ htdocs \ Projects \ php2015 \ vendor \ slim \ slim \ Slim \ Middleware \ MethodOverride.php（92）：Slim \ Middleware \ Flash-> call（）＃10 C：\ xampp \ htdocs \ Projects \ php2015 \ vendor \ slim \ slim \ Slim \ Middleware \ SessionCookie.php（ 110）：Slim \ Middleware \ MethodOverride-> call（）＃11 C：\ xampp \ htdocs \ Projects \ php2015 \ vendor \ slim \ slim \ Slim \ Middleware \ PrettyExceptions.php（67）：Slim \ Middleware \ SessionCookie-> call（）＃12 C：\ xampp \ htdocs \ Projects \ php2015 \ vendor \ slim \ slim \ Slim \ Slim.php（1302）：Slim \ Middleware \ PrettyExceptions-> call（）＃13 C：\ xampp \ htdocs \ Projects \ php2015 \ index.php（53）：Slim \ Slim-> run（）＃14