add smarthost and transport_map capabilities

postfix/defaults/main.yml

@@ -33,3 +33,11 @@ postfix_aliases_rt: []
 #  - queue: IT
 #    url: https://rt.example.com
 #    address: it
+
+postfix_relay_host: ""
+postfix_transport_maps: []
+#  - domain: foo.example.com
+#    server: mail.bar.example.com
+#    port: 2025
+#    protocol: smtp
+#    use_mx: true