Email, snail mail, text messages etc. all need, IMO, options for ONLY allowing incoming messages from known sources. This seems like it is really aiming to do that for Email and I applaud the effort. Hopefully, it will take off in a big, big way.
I think this could work for text messages, too. All new texts could go to a screener and don't notify until you opt-in.
Anyway, nothing against the posted project! I think it's cool.