Add example container that uses ssmtp to forward emails.

This will work for applications invoking /usr/bin/sendmail

It will not work for applications connecting directly to localhost:25.

README.md

@@ -4,8 +4,20 @@ Build:
 
     docker build -t eeacms/postfix . 
 
-Edit the `.secrets` with your smtp authentication.
+Update the `.secrets` with your smtp authentication.
 
 Usage:
 
-    docker run --rm  -t -i --env-file=.secret eeacms/postfix 
+    docker run --rm  -t -i --env-file=.secret --name=postfix eeacms/postfix 
+
+## Example usage
+
+Run:
+    
+    cd example
+    docker build -t example .
+    docker run --rm -it --link=postfix:postfixcontainer example
+    
+    mail test@example.com
+    
+    # mail should be sent by the postfix container
\ No newline at end of file

example/Dockerfile

+FROM layerworx/centos
+
+RUN yum install -y mailx ssmtp
+
+ADD ssmtp.conf /etc/ssmtp/ssmtp.conf
+
+CMD ["bash"]

example/ssmtp.conf

+#
+# /etc/ssmtp.conf -- a config file for sSMTP sendmail.
+#
+# See the ssmtp.conf(5) man page for a more verbose explanation of the
+# available options.
+#
+
+# The person who gets all mail for userids < 500
+# Make this empty to disable rewriting.
+root=postmaster
+
+# The place where the mail goes. The actual machine name is required
+# no MX records are consulted. Commonly mailhosts are named mail.domain.com
+# The example will fit if you are in domain.com and your mailhub is so named.
+mailhub=postfixcontainer
+
+# Where will the mail seem to come from?
+#RewriteDomain=
+
+# The full hostname
+#Hostname=
+
+# Set this to never rewrite the "From:" line (unless not given) and to
+# use that address in the "from line" of the envelope.
+FromLineOverride=YES
+