One of the points of email is that it is asynchronous communication. You can even respond in batches like RMS does. While everyone's email workflow is different

One of the points of email is that it is asynchronous communication. You can even respond in batches like RMS does. While everyone's email workflow is different, it would be a mistake to assume that email was ever designed to be used as an instant-messaging-style communication tool. IRC exists for a reason.