postfix: allow the correct subnet in mynetworks

Signed-off-by: Mattia Rizzolo <mapreri@ubuntu.com>

roles/postfix/templates/main.cf

@@ -23,7 +23,7 @@ myorigin = /etc/mailname
 # yes, it's not accepting stuff for @ubuntu-it.org, that will go into a virtual alias map, maybe.
 mydestination = {{ inventory_hostname }}, localhost
 virtual_alias_maps = hash:/etc/postfix/virtual_domains
-mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128 10.8.0.0/24
+mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128 {{ lxd_subnet }}.0/24
 message_size_limit = 52428800
 mailbox_size_limit = 0
 recipient_delimiter = +