Postmaster Direct is a mailing list program that you have to pay a monthly fee on depending on the number of users that are subscribed. It's very powerful, and I like it a lot. I just got it, but you can find more info at
http://www.postmastergeneral.com.
What Cold Steel wanted to do was have it so that when you register for his message boards, it adds you to the mailing list as well.....this adds more people that are subscribed which in turn (if you have a newsletter with ads) can make you more money.