Updated narrative readme with a little more detail

README.md

@@ -9,6 +9,27 @@ Of the implementations out there, none seemed to do what I wanted from an SMTP
 server, namely emit an event when a message is received. The other
 implementations focused on relaying the message. That's certainly not to say
 that they are wrong, but what I had in mind was something a little different
-from traditional email relay...
+from traditional email relay.
 
-TODO: Finish documenting this!
+As a web developer, I often come across situations where being able to interact
+with a web site via email might come in handy and I would like the toolset to
+be able to do this. Consider the following workflows:
+
+Unsubscribe from mail list
+--------------------------
+
+Many services which send bulk email provide some unsubscribe mechanism for their
+mail shots. Some have a click through to a web page to change your preferences,
+but others have a `mailto:` link to, e.g., _unsubscribe@example.com_. In this
+case an SMTP daemon based on node-smtpevent, would take the from address and use
+this to process the unsubscribe request.
+
+Reply to forum thread
+---------------------
+
+Web forums often offer a mechanism to keep contributors up-to-date with the
+latests posts in a forum thread. If you want to quickly contribute to the thread
+without visiting the web site (e.g. from your smart phone) it may be easier to
+simply reply to the email notification. In this case the daemon would route the
+incoming message back into the forum thread and attribute it using data encoded
+in the to address.