Contentfilter not working

Contentfilter not working because Postfix needs a reload
After service postfix restart or service postfix reload the filter works

OS: Debian 8
PHP: 5.6.30
Plugin: ispconfig3/server/plugins-available/postfix_filter_plugin.inc.php
Affected files:

• '/etc/postfix/header_checks'
• '/etc/postfix/mime_header_checks'
• '/etc/postfix/nested_header_checks'
• '/etc/postfix/body_checks'

Possible remedy:
add exec($conf['init_scripts'] . '/' . 'postfix reload &> /dev/null'); $app->log('Postfix config reloaded ', LOGLEVEL_DEBUG); to the end of the update methode