Yup, look at the headers on some of the duplicate messages. Look closely.
I bet you have a subscriber who's forwarding the mails from your list,
back to the list. The headers might shed some light on this situation.
This is one of the risks you take by having a list with "Send= Public".
You might want to set "Send= Editor,Confirm,Hold" for at least a few days
to help stem the flow of these duplicate messages. If this is an
announcements only list, you should consider making the list edited on a
permanent basis.

On Tue, 29 Jan 2002, Tabariasl, Hamid wrote:

> We have an announcement list that worked fine for quite some times and
> now everytime you send a message to the list, list subscribers are
> receiving hundreds copies of the message?
>
> Any thoughts what may be causing this? Your response is appreciated
>
> Hamid Tabari
>
> Here is the original list configuration:
>
> subscription=open, confirm
> ack=no
> confidential=no
> validate=no
> review=public
> send=editor
> reply-to=list, respect
> send=public
> error-to=owner
> auto-delete =yes,full-auto,probe(10)
> notebook=no
> [log in to unmask]
> [log in to unmask]
> [log in to unmask]
> [log in to unmask]
> hh on
>
>  we made some changes to the above configuration and are waiting on
> response from subscribers:
>
> subscription=open, confirm
> ack=yes
> validate=yes, confirm
> review=owners
> send=editor, confirm
> reply-to=sender, ignore
> send=none
> error-to=owner
> auto-delete =yes,full-auto,probe(10)
> notebook=no
> [log in to unmask]
> [log in to unmask]
> [log in to unmask]
> [log in to unmask]
> hh on
>