PHP Contact form refuses to redirect after sending an Email

Question

I have a PHP contact form that is working fine on localhost(sends an email to my inbox and redirects to another page). However when I upload it to a liveserver and test it, the user input gets submitted to my email inbox but displays the input on the browser and does not redirect to another page(thank-you page). I am using PHPMailer class to send the form.

PHP Form

<?php session_start();

 //INITIALIZE VARIABLES and set to empty values
$name = $phone = $email = $message= $captchaResults= "";
$nameErr = $phoneErr = $emailErr = $checkboxErr= $messageErr= $captchaErr= "";

ini_set('display_errors', 1);
error_reporting(E_ALL);

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

    $valid = true;
    //check if name is empty and performs functions in curly brackets
    if (empty($_POST["name"])) {
       $valid = false;
       $nameErr = "Please fill out this field";
    } 
    else {
        //Passes name throught test input function at the bottom of page
         $name = test_input($_POST["name"]);
        //remove illegal characters from name , Sanitize data
        $nm =filter_var($name, FILTER_SANITIZE_STRING);
       // Validate Data
        if (!preg_match("/^[a-zA-Z\s,.-]{3,30}$/", $nm))          // Regexp requiring letters, spaces, commas and fullstops and should not exceed 30 letters
        {
            $valid = false;
            $nameErr = "Please don't insert numbers*";
        } 
    }

    //check if phone contains numbers
    if (empty($_POST["phone"])) {
        $valid = false;
        $phoneErr = "Please fill out this field";
    } 
    else {
        $phone = test_input($_POST["phone"]);
        if (!preg_match("/^[0-9\s(),+.-]*$/", $phone)) {

            $valid = false;
            $phoneErr = "Please don't insert letters*";
        }
    }

             //check if email is valid
    if (empty($_POST["email"])) {

        $valid = false;

        $emailErr = "Please fill out this field";
        echo'email is empty<br>';
    } 
    else {
        $email = test_input($_POST["email"]);
        //Remove all illegal characters from email
        $em = filter_var($email, FILTER_SANITIZE_EMAIL);

      if (!preg_match("/^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3})$/", $em))
        {
            $valid = false;
            $emailErr = "*Please insert a valid email address*";
        }
    }

        // Check the values from checkbox and POST them to email 
         $value= "";                                           
    //
     if (empty($_POST["checkbox"])) {

        $valid = false;
        $checkboxErr = "Please fill out this field*"; 

    }
    else{
        $checkbox =$_POST["checkbox"];                //Array of values from the checkbox values
            $value= implode(' , ', $checkbox);           //implode values and separate by a comma
                $value = test_input($value);
    } 

    //check if message contains letters and white-space
    if (empty($_POST["message"])) {
       $valid = false;
       $messageErr = "Please fill out this field";
        echo 'Message is empty<br>';
    } 
    else {
        $message = test_input($_POST["message"]);
        //remove illegal characters from url
          $msg =filter_var($message, FILTER_SANITIZE_STRING);

        if (!preg_match("/^[a-zA-Z\s-,:;`~.?()]*$/", $msg))       //Regexp requiring spaces, full-stops, colon, semi-colons brackets, question marks 
        {
            $valid = false;
            $messageErr = "Only letters and spaces are allowed*";
        } 
    }

    //Captcha Results
    $getRandomNumber1 = $_POST["firstRandomNumber"];
    $getRandomNumber2 = $_POST["secondRandomNumber"];
    $getCaptchaResults = $_POST["captchaResults"];

    $totalNumber= $getRandomNumber1 + $getRandomNumber2;

    if($totalNumber == $getCaptchaResults){
    echo'';
    }
    else{$valid = false; 
        $captchaErr="Wrong Answer";}

    //stores name in a session variable to be used in thank-you page    
    $_SESSION["nm"]= $nm;



    require ("PHPMailer/PHPMailerAutoload.php");                      //including phpmailer class

    $mail = new PHPMailer();

    $mail->IsSMTP();                                      // set mailer to use SMTP
    $mail->SMTPDebug = 2;
    $mail->Host = "gator4261.hostgator.com";            // specify main and backup server, 
    $mail->Port = 465;                                //Gmail SMTP port
    $mail->SMTPSecure = "ssl";                     // Connect using a TLS connection
    $mail->SMTPAuth = true;                         // turn on SMTP authorization
    $mail->Username = "info@myemailaccount.com";  // SMTP username
    $mail->Password = "****************";            // SMTP password

    $mail->From = "$em";                         //email of sender
    $mail->FromName = "$nm";                        //name of the sender
    $mail->AddAddress("info@myemailaccount.com", "Petfar Designers");        //email address of recepient and name
    $mail->AddReplyTo($em, $nm);                     //Address to which recepient will reply

    $mail->WordWrap = 100;                                   // set word wrap to 100 characters
    $mail->IsHTML(true);                                          // set email format to HTML
    $mail->Subject = "Contact  Form";    //subject of email

    $mail->Body = "Name: " . $nm . 
                  "<br>Phone: " . $phone . 
                  "<br>Email: " . $em .
                  "<br>Subject: " . $value .
                  "<br>Message: " . $msg ;


    //$mailphp = false;
    if ($valid) {

        // if (!$mailphp) {
        if (!$mail->Send()) {
            echo 'Form could not be sent.';
            echo 'Mailer Error: ' . $mail->ErrorInfo;
            exit;
        } else {
            header('Location:thank_you.php');
        }
    }
}


function test_input($data) {
    $data = trim($data);
    $data = stripslashes($data);
    $data = htmlspecialchars($data);

    return $data;
}

?>

thank-you page

<?php session_start();

?>

<!DOCTYPE html>
<html lang= "en-US"> 
<head>
<title> Thank_you_Page </title>
</head>

<body> 

<div class="container2">
<br> <br> <div class="thanks"> <b> Hello <i> <?php echo $_SESSION["nm"]; ?> </i> ,Your Contact form was successfully sent! One of our agents will reply to your query as soon as possible. <br> Thank you for choosing us </b> </div> 
<br> <br> <a href="contact.php"> Go Back </a>
</div>


</body> 

</html>

Error Message

Warning: Cannot modify header information - headers already sent by (output started at /home4/pwebken/public_html/PHPMailer/class.smtp.php:234) in /home4/pwebken/public_html/contact.php on line 157

Answer 1

You can always use headers_sent() to probe if it's still possible to... send headers. Which is useful to conditionally print any info or apply fallback logic.

if (headers_sent()) {
    die(file_get_contents("thank_you.php"));
}
else{
    exit(header("Location: /user.php"));
}

Answer 2

Instead of using headers header('Location:thank_you.php'); Use echo '<script>location.replace("thank_you.php");</script>';

Hope it helps!