added some simple instructions.

Author: cdornsife

README.md

@@ -1,4 +1,40 @@
 # kubernetes-postfix-relay-host
-A SMTP relay host for transactional based emails.
+A SMTP relay host for transactional based emails from within a k8 cluster.
 
- Alpine/docker/postfix
+## Overview
+This repository contains Kubernetes config files and a docker image to easily set up a SMTP relay for services such as SendGrid.
+
+## Background
+We needed a simple docker image that can be configured with env vars. Also, the functionality is easily overridded by providing an alternate init script. 
+
+# Quickstart
+Run on docker
+```
+docker run --rm -it -p 2525:25 \
+	-e TX_SMTP_RELAY_HOST="[smtp.sendgrid.net]:587" \
+	-e TX_SMTP_RELAY_MYHOSTNAME=tx-smtp-relay.yourhost.com \
+	-e TX_SMTP_RELAY_USERNAME=username \
+	-e TX_SMTP_RELAY_PASSWORD=password \
+	applariat/tx-smtp-relay
+
+```
+Send a test message
+<pre>
+<b>telnet localhost 2525</b>
+220 tx-smtp-relay.yourhost.com ESMTP Postfix
+<b>helo localhost</b>
+250 tx-smtp-relay.yourhost.com
+<b>mail from: [email protected]</b>
+250 2.1.0 Ok
+<b>rcpt to: [email protected]</b>
+250 2.1.5 Ok
+<b>data</b>
+354 End data with <CR><LF>.<CR><LF>
+<b>Subject: What?</b>
+<b>My hovercraft is full of eels.</b>
+<b>.</b>
+250 2.0.0 Ok: queued as 982FF53C
+<b>quit</b>
+221 2.0.0 Bye
+Connection closed by foreign host
+</pre>