{% set config = salt['pillar.get']('postfix:vmail', {}) -%}
{% macro set_parameter(parameter, default=None) -%}
{% set value = config.get(parameter, default) -%}
{% if value is not none -%}
{{ parameter }} = {{ value }}
{% endif -%}
{% endmacro -%}

{# Accept arbitrary parameters -#}
{% for parameter in config -%}
{{ set_parameter(parameter) }}
{% endfor -%}

{{ set_parameter('table', 'mailbox') }}
{{ set_parameter('select_field', 'maildir') }}
{{ set_parameter('where_field', 'username') }}