I am one of those people that doesn't read emails that are longer than 2 paragraphs. I'm sorry, but I don't. I just don't have the time or the patience to read 5 page emails. I'm sure that sounds immature, conceited and worthy of a good eye roll, head shake combination. But I would be way more productive if everyone stuck to a two paragraph email rule.
That is why I like the thought behind three.sentenc.es, which applies a disciplined approach writing short emails. Comes in two, four and five sentence variations as well.