There is one called Email Commander that was a MacUpdate promo awhile back. However, I found it didn't have proper throttling controls (my host only allows 200mails/hour) so thats a no-go. There is one more I heard of called Mailings but I haven't properly looked into that yet.
I know it's not a Mac program, but have you tried phplist? It's free and as long as you have a webhost it's relatively easy to setup and use. I've been using it for a few years and it even does batch emailing (throttling), user controlled subscribe/unsubscribe, personalization, and more. For free I've been very happy with it.
I downloaded MacMassMail and tested it out. I sent a test message to myself, haven't gotten it yet. It leaches onto the Apple Mail program to send, which I don't like. Basically, it sends using the ISP you use for email. I wish it had a feature to set the servers you want to use.
Edit... I just got the test email. It went to my bulk email folder.