Please Advise

[Kevin Merrill <kmerrill @ listserv . nses . com>]

Need your expert help - I keep all of my lists set to "noadvertize" so
that the lists I run will not be easily visible to those not subscrib'ed
to my ists, but have recently found out that when a user sent my Majordomo
server a "wh1ch @" command, he got back all e-mail addresses for all lists
on my server,....seems like a HUGE security hole to me.

Can anyone advise me on a way to prevent this command from working ??

Thanks in Advance,

Kevin Merrill