There are so many of these bland, one-sentence + email box sign-up landing pages that it's hard to really care about your product until you give people a reason to. I would try to do something more original than this, maybe taking a cue from the fact that your product is centered around email, maybe design the splash-page like an inbox? (this is just one idea, the point is to differentiate yourself from every other landing page that took 2 minutes to make with existing one-click "create a landing page" services).
Also, a video or snapshots, or a few use-cases/scenarios would be good, possibly in a separate "about" section.
My 0.02$, in any case good luck!