In PHP form handling, what best practices should be followed to ensure the proper extraction and utilization of user-provided data, such as email addresses, for various functionalities like email sending?

To ensure the proper extraction and utilization of user-provided email addresses in PHP form handling, it is essential to validate the input to ensure it is a valid email address format. This can be done using PHP's built-in filter_var function with the FILTER_VALIDATE_EMAIL filter. Additionally, it is important to sanitize the input to prevent any potential security vulnerabilities, such as SQL injection attacks, by using functions like htmlspecialchars or mysqli_real_escape_string.

// Validate and sanitize user-provided email address
$email = $_POST['email'];

if (filter_var($email, FILTER_VALIDATE_EMAIL)) {
    $safe_email = htmlspecialchars($email);
    // Proceed with sending email or other functionality
} else {
    // Handle invalid email address input
}