We have a list, THURSDAY-SUPPER, which has "Send= Editor, Hold", and a
number of editors and moderators.  Spam mail was submitted to the list
with a forged From address which was the list address.  (Both From and
To addresses were the list address.)  Listserv requested confirmation
from the moderators as usual.  However, the moderation response was
posted to the list:

Your message dated Wed, 30 Sep 2009 23:21:34 -0400 (EDT) with subject
...  has  been  submitted to  the  moderators  of the THURSDAY-SUPPER list.

That response was posted to the list immediately, without moderation
being applied to it.  I would have thought Listserv would never accept
mail from the list address, either due to loop detection or some other
rule.  Is there a way to prevent that from happening in the future?
We're running Listserv 15.0, but I hope there's a solution short of
upgrading.

Peter