Hi there!
I agree with Brian in that your treading dangerously close in name, look and feel to the current market leader and might find yourself getting a C&D or a terse email before you ever hit any real traction. I'd reconsider your brand before moving much further. It'd be a shame if your technical accomplishments get tarnished over some bad PR situation.
Regarding your product, I think email input is a difficult feature to pull off. No matter how simple you make the format, your users will find a way to screw it up. And users will blame your service for the poor experience. Having to defend your product to customers and training them to properly use a product is VERY TOUGH.
Further, if you want email input to be the one feature you use to differentiate yourself from your competition, that feature had better be MAGICAL. Posterous is one example of a company that used email input to help users publish content to their blog as it's key differentiation. They put together a great blog platform, but the email input was their 10-second onboarding. "Email your first blog post us and we'll set everything up for you!" THAT'S MAGIC.
Your differentiation aside, I don't think that's what your biggest problem is. I realize this is an MVP, but I think many people take the MVP thing too literally. If you're launching a product in a market which has (as you state) a lot of competition, your MVP launch should at least perform on-par with the rest of the market. First impressions are hard to fix and launching a sub-par MVP will likely doom you to failure by obscurity.
What you should do: Start thinking about how you want to improve on what's out there. If it's email input, then iterate on that feature over and over until it's like magic. On each iteration, get people to use the feature and see if they like it or hate it. I would even take Brian's suggestion and use Buffer's API so you can focus on THAT feature alone. (And don't get discouraged.)