Сообщение не доходит до моей электронной почты. Каково же решение?

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<?php
 header('Content-Type: text/html; charset=utf-8');
if(isset($_POST['email'])) {

    // email
    $email_to = "mouloublog@gmail.com";
    $email_subject = "Email from:";

    $first_name = $_POST['first_name']; // required
    $last_name = $_POST['last_name']; // required
    $email_from = $_POST['email']; // required
    $telephone = $_POST['telephone']; // not required
 
    $email_message = "Form details below.\n\n";

    function clean_string($string) {
      $bad = array("content-type","bcc:","to:","cc:","href");
      return str_replace($bad,"",$string);
    }
 
    $email_message .= "First Name: ".clean_string($first_name)."\n";
    $email_message .= "Last Name: ".clean_string($last_name)."\n";
    $email_message .= "Email: ".clean_string($email_from)."\n";
    $email_message .= "Telephone: ".clean_string($telephone)."\n";
 
// create email headers
$headers = 'From: '.$email_from."\r\n".
'Reply-To: '.$email_from."\r\n" .
'X-Mailer: PHP/' . phpversion();
@mail($email_to, $email_subject, $email_message, $headers);  
?>
 
<?php
    echo "<script type='text/javascript'>alert('سنتم الرد عليك في البريد الالكتروني الخاص بك لذا قم بفحصه الان وشكراا')</script>";
    echo "<script> window.location.assign('../home.html'); </script>";
?> 
 
 <?php
}
?>

Что я уже пробовал:

<pre><?php
 header('Content-Type: text/html; charset=utf-8');
if(isset($_POST['email'])) {

    // email
    $email_to = "mouloublog@gmail.com";
    $email_subject = "Email from:";

    $first_name = $_POST['first_name']; // required
    $last_name = $_POST['last_name']; // required
    $email_from = $_POST['email']; // required
    $telephone = $_POST['telephone']; // not required
 
    $email_message = "Form details below.\n\n";

    function clean_string($string) {
      $bad = array("content-type","bcc:","to:","cc:","href");
      return str_replace($bad,"",$string);
    }
 
    $email_message .= "First Name: ".clean_string($first_name)."\n";
    $email_message .= "Last Name: ".clean_string($last_name)."\n";
    $email_message .= "Email: ".clean_string($email_from)."\n";
    $email_message .= "Telephone: ".clean_string($telephone)."\n";
 
// create email headers
$headers = 'From: '.$email_from."\r\n".
'Reply-To: '.$email_from."\r\n" .
'X-Mailer: PHP/' . phpversion();
@mail($email_to, $email_subject, $email_message, $headers);  
?>
 
<?php
    echo "<script type='text/javascript'>alert('سنتم الرد عليك في البريد الالكتروني الخاص بك لذا قم بفحصه الان وشكراا')</script>";
    echo "<script> window.location.assign('../home.html'); </script>";
?> 
 
 <?php
}
?>

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