[..]
> do it on a per list basis
>
> QUERY listname WITH NOMAIL FOR *@*

We have 4,400 lists

> It will also be in the Change-Log if you have that turned on, which
> I highly reccomend.

Yes it is useful, but we try not to intefere with our owner's list
configuration, so leave it up to the owner whether they switch that on.

> Or if you only allow private postings to some lists, it might
> be someone
> who gets their email on one account, and can post from
> multiple accounts
> or their email services changes their posting method.

Yes, that is a good point!

Regards
Spencer