The page that follows shows your students' info including emails and the best part is if you scroll all the way to the bottom, you see them all in a box from which you can copy and paste! (I prefer the 'triple-click to highlight all, Ctrl-C to copy, Ctrl-V to paste' method myself.)
The document below details another way, but I haven't found a way to easily copy them all the email addresses at once like the method above.