postfix: add configuration variable for my_networks

postfix/defaults/main.yml

@@ -41,3 +41,5 @@ postfix_transport_maps: []
 #    port: 2025
 #    protocol: smtp
 #    use_mx: true
+
+postfix_my_networks: []

postfix/templates/main.cf.j2

@@ -5,7 +5,7 @@ inet_protocols = all
 myhostname = {{ ansible_fqdn }}
 myorigin = /etc/mailname
 mydestination = $myhostname localhost {{ postfix_domains | join(" ") }}
-mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
+mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128 {{ postfix_my_networks|join(" ") }}
 relayhost = {{ postfix_relay_host }}
 {% if postfix_transport_maps|bool %}
 transport_maps = cdb:/etc/postfix/transport