Error messages always loads when fields are filled in.

suggest.php
<?php 


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

    $name = trim(filter_input(INPUT_POST, "name", FILTER_SANITIZE_STRING));
    $email = trim(filter_input(INPUT_POST, "email", FILTER_SANITIZE_EMAIL));
    $details = trim(filter_input(INPUT_POST, "details", FILTER_SANITIZE_SPECIAL_CHARS));


    if($name == "" || $email == "" || $details == "") {
        echo "Please fill in the details in all form fields";
        exit;
    }

    if($_POST["address"] != "") {
        echo "Bad form input";
        exit;       
    }

    echo "<pre>";
    $email_body = "";
    $email_body .= "Name: " . $name . "\n";
    $email_body .= "Email: " . $email . "\n";
    $email_body .= "Details: " . $details . "\n";
    echo $email_body;
    echo "</pre>";

    //To do - send email

    header("location:suggest.php?status=thanks");
}

$pageTitle = "Suggest a Media Item";
$section="suggest";

include("inc/header.php"); ?>

        <div class="section page">

            <div class="wrapper">

                <h1>Suggest a Media Item</h1>

                <p>Not seeing what you want in our catalog? Let us know!</p>

                <?php if(isset($_GET["status"]) && $_GET["status"] == "thanks") {
                    echo "<p>Thanks for the email,  I&rsquol;ll check out your suggestion shortly!</p>";
                } else { ?>


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

                    <table>
                        <tr>
                            <th>
                                <label for="first_name">Name:</label>

                            </th>
                            <td>
                                <input type="text" id="first_name" name="first_name" />
                            </td>
                        </tr>
                        <tr>
                            <th>
                                <label for="email">Name:</label>

                            </th>
                            <td>
                                <input type="text" id="email" name="email" />
                            </td>
                        </tr>
                        <tr>
                            <th>
                                <label for="suggest">Suggestion:</label>

                            </th>
                            <td>
                                <textarea name="suggest" id="suggest" />Send your suggestions here!</textarea>
                            </td>   

                        </tr>
                        <tr style="display: none">
                            <th>
                                <label for="address">Address:</label>

                            </th>
                            <td>
                                <input type="text" name="address" id="address" />
                                <p>Please leave this field blank. You can safely ignore it.</p>
                            </td>   

                        </tr>
                    </table>

                    <input type="submit" value="Send" />        



                </form>
                <?php  } ?>
            </div>

        </div>

<?php include("inc/footer.php"); ?>