Offishelly, I don't get to choose the MTA, but talking to a
couple of other people here, they also send out bulk mails like
this to other ISPs so I might be able to set up a dedicated
box for this: the server's mail queue is still backed up even
after all the work optimising the script :-( If I can sell this
idea to management and a few other techs, your recommendation
might be very useful.
(PS: kewl name yourself :-)