Don't replace the reply button with the send button without checking for new content in the email
The reply button currently gets replaced by the send button. While this might seem a sensible default primary action in the new context, the awful performance of the service means that it is easy to mis-send a blank email thinking the first click wasn't registered.
I don't like how the send button is in one place and then it is the reply button in other places. It has created many drafts that weren't sent,