php code is not changing the header -

this question has answer here:

• how fix “headers sent” error in php 11 answers

it giving me , not changing header:

warning: cannot modify header information - headers sent (output started @ /home/content/27/10711827/html/contact.php:2) in /home/content/27/10711827/html/contact.php on line 24

here code.

<?php  if (empty($_post) === false){   $errors = array();   $name = $_post['name'];   $email = $_post['email'];   $message = $_post['message'];    if (empty($name) === true || empty($email) === true || empty($message) === true){     $error[] = 'name, email , message required!';   } else{     if (filter_var($email, filter_validate_email) === false){          $errors[] = 'that\'s not valid email address';     }     if (ctype_alpha($name) === false){       $errors[] = 'name must cotain letters';     }    }    if(empty($errors) === true){     mail('houseblendrecords@gmail.com', 'contact form', '$message', 'from: ' . $email);     header('location: contact.php?sent');     exit();   } } 

this happens when code has produced content time you're trying send header. make sure code isn't producing warnings. if you're sure that's not case, make sure there aren't empty lines before opening <?php tag.