I'm using EZMLM right now, and while it seems to work well, I need something
that makes it easier to chop the lists up into multiple messages before
going out.  I just read some stuff on Smartlist, and it's little program
called choplist which looks like it does what I want.  Does Sympa or Mailman
do anything like this?  

Whatever I get is going to have to handle about 20 lists with 150,000 to
400,000 subscribers each.  Each list only goes out once per day, so it's not
high traffic, just a lot of subscribers.  The actual sending of the messages
will be done through a heavily modified qmail setup (my smarthost cluster).
But the list manager will still have to handle bounces.  If I could set it
up to where each outgoing message was split up into 16 messages with 1/16 of
the subscribers on each one, that would be perfect, as my smarthost cluster
has 4 slave servers that get messages distributed to them randomly (so 16
parts would distribute fairly evenly).

Jay