A few months ago we introduced the Messages Page for users to have a way on our site to view responses to their Inquiries. Now it's possible not only to see the messages, but also to Reply to them using this interface. To create a new response, simply touch the Reply arrow in the upper right corner of a message.
The primary way to have these conversations is with your email client, but it may be quicker to send a message using this interface if you're already on this screen.