FreeBSD example

1. download template https://muszak.eu/download/278026/
2. download zabbix agent scripts https://muszak.eu/download/278031/
3. and put this file inside /usr/local/etc/zabbix5/zabbix_agentd.conf.d/zabbix_5_postfix_zabbix_agent_script.bash
4. create postfix.conf  /usr/local/etc/zabbix5/zabbix_agentd.conf/postifx.conf

   UserParameter=postfix.pfmailq,mailq | grep -v "Mail queue is empty" | grep -c '^[0-9A-Z]'
   UserParameter=postfix[*],/usr/local/etc/zabbix5/zabbix_agentd.conf.d/zabbix_5_postfix_zabbix_agent_script.bash $1
   

5. make sure that all conf files are loaded 
6. edit zabbix_agentd.conf and add at bottom

    Include=/usr/local/etc/zabbix5/zabbix_agentd.conf.d/*.conf