When board wide emails are on and domain name is empty (thus servsr_name configuration value is empty), board throws general error upon registration form submit:

General Error

Illegal use of $_SERVER. You must use the request class or request_var() to access input data. Found in C:\Program Files\Apache Software Foundation\Apache2.2\htdocs\phpBB3\includes\functions_messenger.php on line 412. This error message was generated by deactivated_super_global.