> Is it possible limit the post to a list on a IP or domain based
> criteria?

Not with Mailman in its current state, although you can wrap your list
with procmail and write a recipe that checks what IP it came from.

For example

   BADIPS="[^\.](255\.255\.255\.255|140\.177)"

   :0
   * ^Received: from.*$BADIPS
   /dev/null

would dump any message that passed through an IP address matching the
above regular expression into /dev/null (in this case, 255.255.255.255 and
140.177.0.0/16).

See

   http://www.python.org/pipermail/mailman-users/1999-February/000617.html

for procmail/Mailman interaction tips.

Chris