NULL realm reject

Hi, is it possible to configure an instant reject for a certain realm (in proxy.conf)? I'd like to set this for the NULL realm to disable usernames without a suffix. (any other suggestion to accomplish this is welcomed too!) Thanks! -- /--------------------------------------------- | Jan "Velpi" Van der Velpen | Velpi@industria.be || +32 (0) 498 61 24 89 \---------------------------------------------