I've had my phone now about 5 days. And I've tried K-9 Mail and Maildroid. Maildroid is the best for email. There is a free version, which has ads that run at the bottom. And there is a Pro version, which you can purchase (one time fee) of $17.99. I will be purchasing the Pro version because it eliminates the ads running at the bottom of your screen and therefore drains less on your battery. I'm going to use the free version for another few days to make sure it REALLY works the way I like it to and if so, I'll be purchasing it and supporting the developer, so hopefully he can continue to make upgrades to help others out that REALLY need reliable email provided.
Just thought I'd share. 