The best WP newsletter plugin to date!

Control your own mailing list (vs. third-parties), newsletters appear correctly on the client-side regardless of platform or application (i.e., gmail, outlook, mail, yahoo, iPhone, iPad, etc.), easy user-interface and drag-and-drop newsletter creation (no HTML/CSS knowledge required — perfect for handing off to client with minimal training), among other great features. Wysija is awesome and highly recommended.