I love chatbots, but I'm not sure creating a postcard is the correct application. There's so many question to answer. If this was a form there would be only 3 fields and could be complete extremely quickly.
I completely agree chatbots can be slow at collecting information. In the case of Melon Post we look at rivaling the speed of a web form at least with orders to a previously used address. At this point, the benefit of being available from your message box and focus on simplicity will hopefully attract it's own little group of loyal customers!