I am probably too late to answer this question. But anyways....

I have bought about 4 of the less than $50 tablets. They all use Android as the operating system. I make sure that it has an SD slot for an SD or microSD card. So far, all the ones I bought can do anything online that I want to. My kids play minecraft on it mostly, but I use it to watch youtube and browse around on the web. If your email is web based (like yahoo mail, or gmail etc) then you can check email. I can browse forums as well.
If your kindle is the white screen variety, then these tablets don't compare with battery life. But they are all similar in battery life to the Kindle Fire.
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