config.sls

{% macro postconf(key, value) -%}

postconf-{{ key }}:
  cmd:
    - run
    - name:
        - postconf -e {{ key }}='{{ value }}'
    - unless: test "x$(postconf -h {{ key }} )" = 'x{{ value }}'
    - require:
      - pkg: postfix
    - watch_in:
      - service: postfix

{%- endmacro %}

init.sls

{% from "postfix/config.sls" import postconf %}

postfix:
    pkg:
        - latest
    service:
        - running
    
{{ postconf('myorigin', grains['fqdn']) }}
{{ postconf('smtpd_banner', '$myhostname ESMTP') }}