Requirements: Android 1.5+
Overview: From the makers of K9 Mail comes the multi-paned tablet edition of their email client.
Kaiten Mail is an advanced email client for Android. Building on the excellent open-source base provided by K-9 Mail, Kaiten offers a fresh user interface re-imagined for tablets and high-resolution phones.
Built by K-9's original developer, Kaiten is simpler, easier to work with and a whole lot prettier. Frequently used commands are now available in the application's action bar. If you have the screen real-estate, Kaiten's split-screen view lets you see a mailbox and individual messages side-by-side.
Please note that neither K-9 nor Kaiten Mail currently support Exchange ActiveSync.