Actually I would suggest the same setup as we have for LSTSRV-L:

* Send= Public                ; Anyone can post...but...
* Default-Options= Review     ; Aha!  Only people who are set to
                              ; NOREVIEW can post with impunity.
                              ; By default non-subscribers are
                              ; forced into REVIEW mode.  So much
                              ; for random spammers :)
* Reply-To= List,Ignore       ; Replies are forced back to the
                              ; list by default so people should
                              ; be replying to the peer they get
                              ; the mail from.

It makes a little more work for the list owner(s) but in the
end people's mail doesn't get rejected out of hand, and it's
simple to whack the spam (you just don't approve it).

Nathan