7 march 1995 Ottawa
 
You probably could tamper with the from: field but it is never a goo
idea to deviate from accepted network standards.
 
making a list subscribe by owner, confidential and restricting review to
owner and marking all subscribers as concealed from public review is
about as confidential as you can get.
 
Of course you could pgp encrypt each message sent to the list and use an
anonymous server to hide your true identity but someone who wants to
snoop will set up a mail transport site on the net and snoop at the
headers of the mail in transit.
 
There are some bbs which routinely assign an alias to their users for
use on local conferences.  I know of one such bbs with a discussion
group for teens with aids and the kids can talk freely about their
concerns and surprisingly are extremely good about playing by the rules
about no flames etc.