App Name: K-9mail

Description: “K-9 Mail is an open source email client focused on making it easy to chew through large volumes of email” (from their wiki page). K-9 is one of numerous email clients for Android. It contains numerous features such as POP3, IMAP, Exchange 2003/2007, new mail notifications, signatures, multi-accounts.  You can save emails to SD and manage your various email accounts via your Android device.

Cost:  Free, open source

Developer: K-9 Dog Walkers

Excellent K-9 mail app for Android keeps your messages on a leash – ARS Technica

K9 Mail – Android Tapp

MKB Reviews: K-9 Mail  (video) -DroidDog

K9 Mail Android App Review  (video) – Hemorrdroidsnet