That looks neat in a video. But as the person that receives the email, I would not feel valued at all by the thought that Joe doesn't even take the time to reply but instead lets a robot reply for him.

If you don't want to take the time to reply, then don't bother sending me anything at all. And it's not about having a crazy schedule. We have time. In fact, we have more time than ever before because robots already automate repetitive tasks. But a human interaction is not a repetitive task IMO.