Send= Private merely means only subscribers can post to the list.
If a spammer subscribes, he can post to the list.
 
If your sub is open, you might change it to Subscription= Open,Confirm
which will deter a lot, not all, spammers.  To catch the ones who are
willing to confirm their subs you can put in  Default-Options= Review
so that even if they do "sub to spam" it'll come to you for approval.
Of course you'll periodically want to set "good" subscriptions to noreview
(which is what I'm doing now) or you can just set the subs norev one at
a time as they post to the list (if the list is a large one 3/4s never
post to the list anyway so it doesn't matter if they're set review or
noreview).
 
Be thankful Eric's "spam-o-meter" caught this one for you.
 
Douglas
       Douglas Winship   Hays County, Texas  [log in to unmask]
                    Secondary AUTOCAT Listowner
                              MEDLAB-L