I found the program TouchDown the best. It cost around $14.99, maybe lower now. It syncs really well with Exchange. It even syncs with Exchange Tasks. Why buy anything else!
I own a Thunderbolt and I've tried several different email apps but each one seems to have some shortcoming. I've used and experienced problems with the stock app, Gmail, and K-9. What app do you recommend, either free or fee?....Thanks.