I personally think we should all try to make it as individual as possible. So that if they actually read them, it won't appear as if it were some robot mailer. But generally you would want to have a short sob story, 3 paragraphs max (these people don't have all day). Just explain what your situation is and why you feel keeping the 1,500 rule is the right choice. And most importantly that it's all about the moolah.