Mojo - if you need PM me since I still have older versions somewhere on my hdd that are free, since newer versions are paid scripts.
Link:
http://mojo.skazat.com/installation/
(now it's called Dada Mail and it's paid software now)
also a good freesoftware is phpList -
http://www.phplist.com/, but you'll spend like 2 days in configuring it...