submit_contact_form.php

<?php
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    // Sanitize and validate inputs
    $name = htmlspecialchars(trim($_POST['name']));
    $email = filter_var($_POST['email'], FILTER_SANITIZE_EMAIL);
    $subject = htmlspecialchars(trim($_POST['subject']));
    $message = htmlspecialchars(trim($_POST['message']));

    // Check for empty fields
    if (empty($name) || empty($email) || empty($subject) || empty($message)) {
        echo json_encode(['status' => 'error', 'message' => 'All fields are required']);
        exit;
    }

    // You can add more validation here (like checking the email format)

    // Set up email parameters (for example, using mail() function or a library like PHPMailer)
    $to = 'your_email@example.com';
    $headers = "From: $email\r\n";
    $headers .= "Reply-To: $email\r\n";
    $headers .= "Content-Type: text/plain; charset=UTF-8\r\n";
    
    // Send email
    if (mail($to, $subject, $message, $headers)) {
        echo json_encode(['status' => 'success', 'message' => 'Your message has been sent.']);
    } else {
        echo json_encode(['status' => 'error', 'message' => 'Unable to send your message.']);
    }
} else {
    echo json_encode(['status' => 'error', 'message' => 'Invalid request method.']);
}
?>