Oh, in looking at this:
> ---
> Ed Agro <[log in to unmask]>
> http://listserv.acsu.buffalo.edu/archives/zamir-chat-list.html

I make the assumption that your list is at Buffalo.  I promise you
that
query listname with conceal for *@*

very definitely does work just fine *if* that list truly has any
subscribers who have set the CONCEAL option.  That is where my large
lists are and I assure you it works as specified.     Douglas