How can I fix my list header to reject non-subscribers' postings to my
moderated list ([log in to unmask]) with around 1200 rock-gardening
subscribers?. Most people are lurkers and listowner-moderated, and most
of the active posters self-moderated.  New subscribers are moderated.

Non-subscribers' postings -- mostly spam -- are sent to the moderator
for approval, as are, of course, the postings of listowner-monitored
subscribers.  I filter out the regular spammers, but a great deal still
comes to me for approval and requires scrolling way down the approval
page to be sure it's not from subscribers.  My present settings are:
 Subscription=    By_owner
 Send=            Editor,Hold,Confirm
 Editor=          [log in to unmask]
 Moderator=       All,[log in to unmask]
 Notify=          Yes
 Reply-to=        List,Ignore
 Review=          Private