I have an announcement list that should only allow owners and editors to
post to the list. Someone who is neither an owner or editor has been able to
post to the list twice. I  haven't been able to find what would cause this
in the manual. I've tried to replicate the problem on my sample list and
haven't been able to.

I  haven't been able to contact the list owner who brought the problem to my
attention so I haven't asked whether she the posted message came to her with
the paragraph at the top asking her to forward the message to the list if
she wants to. It looks to me like the person's email bypassed the list
owner's approval though.

Here's the header of the list with email addresses removed. I've left the
real names to show that the person posting to the list isn't any of these
people. The name of the person who has posted to the list without permission
is Melanie Barnes. 

PUT RVS-L LIST PW=XXXXXXXX
*
* Offical Administrative Communication for RVS Campus
*
* Owner= (Pam Sutton)
* Editor= (Pam Sutton)
* Editor= (ACC President's Office)
* Editor= (Gerry Tucker)
* Editor= (Alice Swayze)
* Editor= Phyllis Kalz)
* Editor= (Rhonda Fenner)
* Editor= (Virginia Boyd)
* Editor= (Pat Stubbs)
* Editor= (Steve Kinslow)
* Editor= (Sylvia Partida)
* Editor= (Ben Ferrell)
* Editor= (Charles Lavender)
* Editor= (Frank Taylor)
* Editor= (Soon Merz)
* Editor= (Esther Buzard)
* Editor= (Mary Hensley)
* Notebook= No
* Errors-To= [log in to unmask]
* Subscription= Owner
* VALIDATE= No
* Review= Owners
* Send= Editor
* Reply-To= Sender,Respect
* Sender= None
* Auto-Delete= No
* CONFIDENTIAL= Yes