This is in response to two different postings.
 
Forging subscribe/unsubscribe is easy, it's a fact of listowner life.
There are a couple of ways you can block forged subscriptions.
 
If you want subscribers to be able to subscribe themselves, put, in
your list header:
 
Subscribe= Open,Confirm
 
This will cause LISTSERV to send out a "confirmation" message to which
the potential subscriber must respond within a certain period of time.
The forger won't get the message so can't respond.  Instructions on how
to respond are included in the "confirmation" message.
 
The other technique is to put in your list header:
 
Subscribe= By_Owner
 
This sends all subscribe commands to the listowner, who must manually add
all subscribers.  This is generally used by lists which wish to restrict
discussion to a very specific topic among a small group of people with
knowledge in the area.  Often, the listowner will send a questionaire
which must be completed and returned before the person will be added to
the list.
 
As to anti-spam, by having items from non-subscribers sent for approval
while items from subscribers are posted directly, put in your header:
 
Send= Editor
Editor= userid@node,(listname)
 
example:
 
Send= Editor
Editor= [log in to unmask],(AUTOCAT)
 
If you have a usenet gateway, and are using 1.8b, you can also have
items from a usenet gateway sent for approval with REVIEW.  To do this
you SET the gateway address REVIEW.  This is a regular SET command, like
for setting someone NOMAIL, it doesn't go in the header.  For example,
if your gateway is [log in to unmask]  it would be:
 
SET listname REVIEW for [log in to unmask]
 
N.B. The approval technique is different for items from non-subscribers
and for REVIEW items, the first using the "forward" technique and the
latter using the "ok" technique, so pay attention if you have both.
 
Douglas
 
       Douglas Winship   Hays County, Texas  [log in to unmask]
                    Secondary AUTOCAT Listowner
                              MEDLAB-L