OpenShift PEAR发送电子邮件

我在openshift服务器上安装了pear邮件包。

然后，我编写了这段php代码，让用户从web表单向我发送电子邮件。我没有收到错误输出，但是我无法在我的电子邮件地址收到消息。

<?php
    require_once "Mail.php";
    if($_POST)
    {
        $recipients = "myemailaddress";        
        //check if its an ajax request, exit if not
        if(!isset($_SERVER['HTTP_X_REQUESTED_WITH']) AND strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) != 'xmlhttprequest') {
        //exit script outputting json data
        $output = json_encode(
        array(
            'type'=>'error', 
            'text' => 'Request must come from Ajax'
        ));
        die($output);
    } 
    //check $_POST vars are set, exit if any missing
    if(!isset($_POST["userName"]) || !isset($_POST["userEmail"]) || !isset($_POST["userSubject"]) || !isset($_POST["userMessage"]))
    {
        $output = json_encode(array('type'=>'error', 'text' => 'Input fields are empty!'));
        die($output);
    }
    else
    {
        //Sanitize input data using PHP filter_var().
        $user_Name        = filter_var($_POST["userName"], FILTER_SANITIZE_STRING);
        $headers['From'] = filter_var($_POST["userEmail"], FILTER_SANITIZE_EMAIL);
        $headers['To'] = $recipients;
        $headers['Subject'] = filter_var($_POST["userSubject"], FILTER_SANITIZE_STRING);         
        $body = filter_var($_POST["userMessage"], FILTER_SANITIZE_STRING);  
        $params['sendmail_path'] = '/usr/lib/sendmail';
        //additional php validation
        if(strlen($user_Name) < 4) 
        {
              // SOME CODE HERE
        }           
        $mail_object =& Mail::factory('sendmail', $params);
        $sentMail = $mail_object->send($recipients, $headers, $body);    
        if(PEAR::isError($sentMail))
        {
            $output = json_encode(array('type'=>'error', 'text' => 'Could not send mail! Please check your PHP mail configuration.'.$sentMail->getMessage()));
            die($output);         
        }
        else
        {
            $output = json_encode(array('type'=>'message', 'text' => 'Email sent successfully! <br/>'.$user_Name .' thank you for your email.'));
            die($output);   
        }
    }
}
?>