Add a field on your registration form <label for=”secret_reg_code”>Secret Code: </label> <input type=”text” name=”secret_reg_code” id=”secret_reg_code” value=”” /> then in your plugin file or in function.php add define(‘MY_SECRET_REG_CODE’, ‘fdsfgadsfgdf’); function check_for_reg_secret_code($errors, $sanitized_user_login, $user_email) { if ( defined(‘MY_SECRET_REG_CODE’) && trim($_POST[‘secret_reg_code’]) != MY_SECRET_REG_CODE ) { $errors->add( ‘secret_code_error’, __(‘<strong>ERROR</strong>: Enter a valid code postal code.’, ‘your_text_domain’) ); } return … Read more