<?php
if(isset($_POST['submit'])){
    $to = "yourmail@mail.com"; // Replace with your own email address
    $name = $_POST['name'];
    $email = $_POST['email'];
    $message = $_POST['message'];
    $headers = "From: $name <$email>";
    
    // Check if all required fields are filled out
    if(empty($name) || empty($email) || empty($message)){
        header("Location: http://www.xxx.com");
        exit;
    }
    
    // Send the email
    mail($to, "New message from website", $message, $headers);
    echo "Message sent!";
}
?>

<form method="post" action="">
    <label>Name:</label>
    <input type="text" name="name" required>
    
    <label>Email:</label>
    <input type="email" name="email" required>
    
    <label>Message:</label>
    <textarea name="message" required></textarea>
    
    <input type="submit" name="submit" value="Send">
</form>

หรือ 

<?php
if(isset($_POST['submit'])){
    $to = "youremail@example.com"; // Replace with your own email address
    $name = $_POST['name'];
    $email = $_POST['email'];
    $message = $_POST['message'];
    $headers = "From: $name <$email>";
    
    // Check if all required fields are filled out
    if(empty($name) || empty($email) || empty($message)){
        header("Location: http://www.cymiz.com");
        exit;
    }
    
    // Send the email
    mail($to, "New message from website", $message, $headers);
    echo "Message sent!";
    exit;
}
?>

<form method="post" action="">
    <label>Name:</label>
    <input type="text" name="name" required>
    
    <label>Email:</label>
    <input type="email" name="email" required>
    
    <label>Message:</label>
    <textarea name="message" required></textarea>
    
    <input type="submit" name="submit" value="Send">
</form>