How to turn off 'who'?

[Steve Loft <steve @ klaatu . demon . co . uk>]

I'm just setting up a mailing list, and I don't want anyone to be able to do
a 'who' - not even subscribers to the list.  I can't find an option to do
this, and looking at the code, even though I don't really know Perl, seems
to confirm that there isn't one.  Is my only option to edit the code?

Steve