Newsletter plugin options?

I'm looking for an email newsletter manager and I'm curious about options. I found MailPress, but with almost no docs, I can't really tell what it does or if it's robust.

I'm looking for something that can handle subscriber management, customization, multiple-posts per mailing, embedded ads, and more customization.

Any recommendations for a robust system? I don't want to use a commercial service since I have my own servers. Thanks!