Sorry, I didn't mean to reply to you, it was just an open question because the OP had it in the first post....
I encountered a server today which responded to /LIST thusly...
-> irc.server.com LIST
<- :irc.server.com 481 yournick :Permission Denied: Insufficient privileges
mIRC did not realize that 481 was the server's official response to the /LIST command
