I also recently started to use mailing list in my blog. I thought a mailing list will be useful in iOS and Mac apps as well. So I started a project building a universal framework for both the iOS and Mac platforms, complete with UIs. It illustrates the concept of code sharing between iPhone, iPad, and Mac apps with just one codebase. The fact that you got 30,000 emails proves its viability. The project is at https://github.com/rayvinly/DevNewsletter