diff --git a/postfix/files/main.cf b/postfix/files/main.cf
index 2f7bf48..ae61bed 100644
--- a/postfix/files/main.cf
+++ b/postfix/files/main.cf
@@ -5,7 +5,14 @@
 {% macro set_parameter(parameter, default=None) -%}
 {% set value = config.get(parameter, default) -%}
 {% if value is not none -%}
+  {%- if value is number or value is string %}
 {{ parameter }} = {{ value }}
+  {%- elif value is iterable %}
+{{ parameter }} =
+    {%- for v in value %}
+       {{ v }},
+    {%- endfor %}
+  {%- endif %}
 {%- do processed_parameters.append(parameter) -%}
 {% endif -%}
 {% endmacro -%}
@@ -43,15 +50,14 @@
 {{ set_parameter('myhostname', grains['fqdn']) }}
 {{ set_parameter('alias_maps', 'hash:' ~ postfix.aliases) }}
 {{ set_parameter('alias_database', 'hash:' ~ postfix.aliases) }}
-{{ set_parameter('mydestination', grains['fqdn'] + ', localhost, localhost.localdomain, ' + grains['domain'] ) }}
+{{ set_parameter('mydestination', [grains['fqdn'], 'localhost', 'localhost.localdomain', grains['domain']]) }}
 {{ set_parameter('relayhost', '') }}
-{{ set_parameter('mynetworks', '127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128') }}
+{{ set_parameter('mynetworks', ['127.0.0.0/8', '[::ffff:127.0.0.0]/104', '[::1]/128']) }}
 {{ set_parameter('mailbox_size_limit', '0') }}
 {{ set_parameter('recipient_delimiter', '+') }}
 {{ set_parameter('inet_interfaces', 'all') }}
 {{ set_parameter('message_size_limit', '41943040') }}
-{{ set_parameter('smtpd_relay_restrictions', 'permit_mynetworks permit_sasl_authenticated defer_unauth_destination') }}
-
+{{ set_parameter('smtpd_relay_restrictions', ['permit_mynetworks', 'permit_sasl_authenticated', 'defer_unauth_destination']) }}
 
 {% if 'virtual' in pillar.get('postfix','') %}
 virtual_alias_maps = hash:/etc/postfix/virtual