Well, maybe you don't follow as many startups as I do, but we, who are early technology adopters, get thousands of emails a day from all kinds of services we've tried out. So, if you care about us, busy technology professionals, the essence of your email should be in the subject line, especially when you expect time-sensitive actions from them or destruction could follow if they skip your email! Absolutely every other service puts that sense of urgency in the subject line! Instead of defending your position, learn from my experience as it's really huge!