private mailing lists

[Steve Kotsopoulos <steve@ecf.toronto.edu>]

we're running zmailer-2.2e6, and had setup some class mailing lists
so that instructors could mail them easily (about 100 students per class).

It wasn't long before students started advertising 'book for sale' to
10 lists at a time, with 1000 copies of that message going into various
mailboxes. Our short-term solution was to remove the lists, but the 
profs miss them. Ideally, we'd like the lists to only be available
to certain people.

Is there any way to have restricted mailing lists, so that profs can
spam the students, but the students can't megaspam each-other?