(IAAC) SPAM from the list

I have written the following to Mr. Gramer regarding
some of the SPAM we have recieved via this list and
he suggested I post it here for discussion.
Here's my original e-mail to him:
>A few days ago, I recieved spam from the list (I'm sure you
>saw it).  I already made a complaint to the right place.
>I was wanting to make sure you have the list configured to
>reject any posts from addresses not subscribed to the list.
>This generally gets rid of most junk mail.
>Oh yeah, and I haven't checked (but I should!) but make
>*completely sure* that the user list is not retrievable
>from majordomo.  Junk mailers love to steal addresses from
He made the following comments:
> I only suggest we start a discussion on this is because I
> wanted to allow non-subscribers to submit their observing logs
> along with subscribers: this allows more advanced observers to
> "share their wisdom" without necessarily having to receive
> everybody's logs themselves.
> Still, I can understand why you might not want to be spammed,
> too! One thing I might be able to do is tweak the "majordomo"
> scripts to filter out anything which doesn't have an "Obj:" or
> "Object:" in the Subject line... Also, I can do the "private
> who" config change right now: there's no reason I can think of
> why non-subscribers might want to "who" this list, except for
> spamming purposes...
So what do you all think?  I agree with what he is saying as
I would rather it be as open as possible.  But then again
SPAM will make the list progressively more useless until
there is nobody left subscribed.  It's happened before.
The suggestion that the list be configured to reject postings
without a certain tag in the subject line sounds like a good one
and should work.  Would the list send tell them to put it in if
they hadn't?  That should still be ok I think since they usually
blindly send the stuff out with no manual intervention.
Any suggestions/concerns?
And check out The Coalition Against Unsolicited Commercial Email
at http://www.cauce.org.
                This mailbox is Spam filtered.
Unsollicited commercial e-mails go automatically to /dev/null.