Interesting concept. I did sign up to test it out. However, I think that voice control is not practical with the amount of email we receive on daily basis. Some people will receive more than 100 messages per day that needs to be answered and a voice activated software will not cut it.
However, looking beyond this challenge, the idea is still cool and having an AI assistant to sort out your inbox will be certainly a breakthrough technology. Besides web, email is perhaps one of the greatest innovations of the 20th century but it needs to be brought in the 21st, i.e Email 2.0.
You are right, it doesn't have to be a voice-only interface. rather, voice UI is a starting point for us, since that is a use case we already understand well. But it could work just as well with written/texted instructions to your assistant.
However, looking beyond this challenge, the idea is still cool and having an AI assistant to sort out your inbox will be certainly a breakthrough technology. Besides web, email is perhaps one of the greatest innovations of the 20th century but it needs to be brought in the 21st, i.e Email 2.0.