Using procmail to filter list traffic

Hi.

Sorry if this is an FAQ, but I can't figure out how to do it with procmail.
What I want to be able to do is setup a mailing list, and then filter
incoming traffic to the list to ensure that only a designated number of
people are allowed to send mail to it (all other mail to it is to be
dropped on the floor).

I thought this would be relatively straight forward, using something
like:

        :0                                      # forward valid mail
        * ^From.*(legaladdress(_at_)some(_dot_)domain)
        <<mailing list>>

        :0                                      # sink everything else
        /dev/null

However, I have two problems:

        1. How do I forward the messages to "mailing list", where the
           members of the list are kept in a file elsewhere on the
           system?

        2. How do I make it look `transparent', that is, as though the
           mail came from the original sender, not the intermediate
           procmail account.

If there is a cleaner way of doing the above, I'd be glad to hear it.
Thanks for any help or pointers.
 
/rns
--
Robert Sturrock                        _-_|\   E-mail: 
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