It's not a full solution to your issue (and apologies if you are already aware of this), but a double tap on the home button brings up a list of recent tasks, and your email app should be the left-most one and you can just tap on that to get back to the mail that you were reading.
On the comment about placing the cursor, I have the opposite - I rarely have an issue on my iPhone/iPad, but I cannot for the life of me get the cursor on my Galaxy SII to go to where I want it to.
It is odd isn't it? Maybe our fingers learn different tools better? I LOVE the android keyboard, stock or the various add ons - but so many iOS friends just can't get to grips with it. But I storm along on my (now dead) Dell Streak and Note, and struggle to write anything on my iPod touch.
I wonder if there should be a keyboard that works just like the iOS one for Android, for those trying to migrate ;)
An Apple-alike one would be great. With the standard Samsung one I struggle to put two words together without a mistake, whereas with my iPhone I managed to type a 3 paragraph email while I was walking home last night and managed about two minor errors in the whole thing.
Admittedly I do like the SwiftKey keyboard, and I keep meaning to buy it (my trial ran out and I've not got round to associating a credit card with my Google account). The single best thing about Android for me is that you can at least swap out most of the things that you don't like about the stock OS.
On the comment about placing the cursor, I have the opposite - I rarely have an issue on my iPhone/iPad, but I cannot for the life of me get the cursor on my Galaxy SII to go to where I want it to.