Validation message not showing up, extra credit php

<?php 


if ($_SERVER["REQUEST_METHOD"] == "POST") {

    // get the contact form data for each of the fields
    $name = trim($_POST["name"]);
    $email = trim($_POST["email"]);
    $message = trim($_POST["message"]);

    $error_message=array(); 

    // check if fields are blank
    if ($name == "" OR $email == "" OR $message == "") {
        $error_message[0] = "You must specify a value for name, email address, and message.";


    }

   ///check that none of the fields have malicious code

     foreach($_POST as $value ){
        if( stripos($value,'Content-Type:') !== FALSE ){
           $error_message[1] = "There was a problem with the information you entered.";    
           }
        }



    ///spam honeypot is left blank
    if ($_POST["address"] != "") {
        $error_message[2] = "Your form submission has an error.";

    }

    require_once("inc/phpmailer/class.phpmailer.php");
    $mail = new PHPMailer();

   ///check that email is in a valid format
    if (!$mail->ValidateAddress($email)){
        $error_message[3] = "You must specify a valid email address.";
    }


  //// if its not set, send the email 
    if(!isset($error_message)){
    $email_body = "";
    $email_body = $email_body . "Name: " . $name . "<br>";
    $email_body = $email_body . "Email: " . $email . "<br>";
    $email_body = $email_body . "Message: " . $message;

    $mail->SetFrom($email, $name);
    $address = "orders@shirts4mike.com";
    $mail->AddAddress($address, "Shirts 4 Mike");
    $mail->Subject    = "Shirts 4 Mike Contact Form Submission | " . $name;
    $mail->MsgHTML($email_body);

    if($mail->Send()) {
      header("Location: contact.php?status=thanks");
      exit;
     } else {
         $error_message[4] = "There was a problem sending the email" . $mail->ErrorInfo;
       }
    } 

}


?>

<?php 
$pageTitle = "Contact Mike";
$section = "contact";
include('inc/header.php'); ?>

    <div class="section page">

        <div class="wrapper">

            <h1>Contact</h1>

            <?php if (isset($_GET["status"]) AND $_GET["status"] == "thanks") { ?>
                <p>Thanks for the email! I&rsquo;ll be in touch shortly!</p>
            <?php } else { ?>



                <?php
                   if (!isset($error_message)){
                     echo '<p>I&rsquo;d love to hear from you! Complete the form to send me an email.</p>';
                   } //else {
                    // echo '<p class="message">' . $error_message . '</p>';
                  // }

                   foreach ($error_message as $error) {
                       echo '<p class="message">' . $error . '</p>';
                       exit;
                    }

                ?>

                <form method="post" action="contact.php">

                    <table>
                        <tr>
                            <th>
                                <label for="name">Name</label>
                            </th>
                            <td>
                                <input type="text" name="name" id="name" value="<?php if (isset($name)){echo htmlspecialchars($name);}?>">
                            </td>
                        </tr>
                        <tr>
                            <th>
                                <label for="email">Email</label>
                            </th>
                            <td>
                                <input type="text" name="email" id="email" value="<?php if (isset($email)) {echo htmlspecialchars($email);}?>">
                            </td>
                        </tr>
                        <tr>
                            <th>
                                <label for="message">Message</label>
                            </th>
                            <td>
                                <textarea name="message" id="message"><?php if (isset($message)) {echo htmlspecialchars($message);} ?></textarea>
                            </td>
                        </tr> 
                        <tr style="display: none;">
                            <th>
                                <label for="address">Address</label>
                            </th>
                            <td>
                                <input type="text" name="address" id="address">
                                <p>Humans (and frogs): please leave this field blank.</p>
                            </td>
                        </tr>                   
                    </table>
                    <input type="submit" value="Send">

                </form>

            <?php } ?>

        </div>

    </div>

<?php include('inc/footer.php') ?>