[Mailman-Users] Rejecting Spam Emails

[trichard at techovations.com]

I have spamassassin installed on my mail server.  I'm getting a ton of
spam sent to my mailing list which I have it being blocked unless you are
a registered user.  Is there a way to automatically reject emails with
particular works in the subject?  The spam emails I detect get :SPAM:
added to the subject.  I would like to remove these without having to
manually do it, but I still want unapproved user messages sent to me for
approval.

Any ideas,
Thanks,
Troy