Beef up the example inventory

Signed-off-by: martin f. krafft <madduck@madduck.net>
diff --git a/examples/classes/mail/init.yml b/examples/classes/mail/init.yml
new file mode 100644
index 0000000..8751beb
--- /dev/null
+++ b/examples/classes/mail/init.yml
@@ -0,0 +1,2 @@
+applications:
+  - postfix
diff --git a/examples/classes/mail/relay.yml b/examples/classes/mail/relay.yml
new file mode 100644
index 0000000..28d3b26
--- /dev/null
+++ b/examples/classes/mail/relay.yml
@@ -0,0 +1,6 @@
+classes:
+  - mail
+parameters:
+  mail:
+    role: relay
+    port: 587
diff --git a/examples/classes/mail/satellite.yml b/examples/classes/mail/satellite.yml
new file mode 100644
index 0000000..8a27c92
--- /dev/null
+++ b/examples/classes/mail/satellite.yml
@@ -0,0 +1,8 @@
+classes:
+  - mail
+parameters:
+  mail:
+    role: satellite
+    smtp_relay: smtp.example.org:587
+    smtp_relay_fingerprint: 45:88:ff:11:b0:be:39:c8:30:2a:84:bd:fc:6c:52:ff:76:d4:c5:41
+    tls: enforce
diff --git a/examples/classes/mail/server.yml b/examples/classes/mail/server.yml
new file mode 100644
index 0000000..5e0064d
--- /dev/null
+++ b/examples/classes/mail/server.yml
@@ -0,0 +1,5 @@
+classes:
+  - mail
+parameters:
+  mail:
+    role: server