Mailing List Software

I'm looking for software that will run in the DASP environment that will allow me to moderate a mailing list.


The requirements are as follows:


Posts are accepted only from people subscribed to the list.
Outsiders should be prevented from posting to all members.
When a subscriber sends mail to the list address, all subscribers get the message.
All posts go to the Moderator first for approval before being distributed to the subscribers.


Any ideas?


Thanks...