OSCLASS Spam registration

[MacFas]

IS this code correct? i found this code from a website but not related to osclass...''Hi, how can I allow only gmail, ymail, and hotmail emails only when user registration on osclass? to prevent spam? is there any code?

function is_valid_email_domain($login, $email, $errors)
{
    $valid_email_domains = array(
        "gmail.com",
        "yahoo.com"
    );
    // whitelist email domain lists
    $valid = false;
    foreach ($valid_email_domains as $d)
    {
        $d_length = strlen($d);
        $current_email_domain = strtolower(substr($email, -($d_length) , $d_length));
        if ($current_email_domain == strtolower($d))
        {
            $valid = true;
            break;
        }
    }
    // if invalid, return error message
    if ($valid === false)
    {
        $errors->add('domain_whitelist_error', __('<strong>ERROR</strong>: you can only register using @gmail.com or @yahoo.com emails'));
    }
}
add_action('register_post', 'is_valid_email_domain', 10, 3);