Have you changed any of the code (other than what we discussed earlier in the thread)? If you look at join.cgi, you will see it do some checks before it does the unless($IN->param('do')) condition. When you're doing join.cgi?domain=zapmail.org, do=... isn't set, so it should return GMail::NoAuth->print_page(...). I'm not sure why it's doing what it's doing. I'd have to get ssh or admin.cgi access to take a closer look.

Adrian