I've got a little problem when I try to use my contact form on my website HTML page. It is a simple landing page with a form in the lower end, but when I try to send the message from the form, the page start to buffer and a blank page with an error appears. The error is "HTTP ERROR 500", so basically can't connect with the server. Can someone help me?
Here's the HTML code:
<form class="contact-form form" method="POST" action="contact.php">
           <div class="contact-form-content">
                  <div class="row">
                       <div class="col-lg-6 col-md-6 col-sm-6">
                           <div data-100p-top="transform[swing]:translateX(-25px);opacity[swing]:0" 
                                data-75p-top="transform[swing]:translateX(0);opacity[swing]:1">
                                        <div class="form-group has-feedback">
                                                <input type="text" class="form-control" 
                                                       placeholder="Enter name" name="cf_name">
                                     <span class="glyphicon glyphicon-user form-control-feedback"></span>
                                        </div>
                                            <div class="form-group has-feedback">
                                                <input type="email" class="form-control" 
                                                       placeholder="Enter email" name="cf_email">
                                <span class="glyphicon glyphicon-envelope form-control-feedback"></span>
                                        </div>
                                    </div>
                                </div>
                                <div class="col-lg-6 col-md-6 col-sm-6">
                                <div data-100p-top="transform[swing]:translateX(25px);opacity[swing]:0" 
                                     data-75p-top="transform[swing]:translateX(0);opacity[swing]:1">
                                        <div class="form-group">
                                            <textarea class="form-control" rows="3" cols="40" 
                                                      placeholder="Your Message" name="cf_message">
                                            </textarea>
                                        </div>
                                    </div>
                                </div>
                            </div>
                            <div class="row">
                                <div class="col-md-6 col-md-offset-6">
                                <div data-100p-top="transform[swing]:translateX(25px);opacity[swing]:0" 
                                     data-75p-top="transform[swing]:translateX(0);opacity[swing]:1">
                                       <button type="submit" class="btn btn-transparent btn-lg btn-block" 
                                                value="Send">
                                            <span class="icon icon-basic-mail"></span> Send
                                        </button>
                                    </div>
                                </div>
                            </div>
                        </div>
                    </form>
And here's the "contact.php" code:
<?php
$field_name = $_POST['cf_name'];
$field_email = test_input($_POST['cf_email']);
$field_message = $_POST['cf_message'];
$mail_to = 'example.example@gmail.com';
$subject = 'Message from website '.$field_name;
$body_message = 'From: '.$field_name."\n";
$body_message .= 'E-mail: '.$field_email."\n";
$body_message .= 'Message: '.$field_message;
$headers = 'From: '.$field_email."\r\n";
$headers .= 'Reply-To: '.$field_email."\r\n";
$mail_status = mail($mail_to, $subject, $body_message, $headers);
if (!filter_var($field_email,FILTER_VALIDATE_EMAIL)) { ?>
<script language="javascript" type="text/javascript">
    alert('Invalid email format. Try again or send an email to example.example@gmail.com');
    window.location = 'index.html';
</script>
<?php
}
else
{
if ($mail_status) { ?>
<script language="javascript" type="text/javascript">
    alert('Thank you for the message. I will contact you shortly.');
    window.location = 'index.html';
</script>
<?php
}
else { ?>
<script language="javascript" type="text/javascript">
    alert('Message failed. Please, send an email to example.example@gmail.com');
    window.location = 'index.html';
</script>
<?php
}}
?>
Thank you sooo much for the help!
