Netdata Postfix Alarm

/etc/netdata/health.d/postfix.conf:

template: postfix_local_queue
      on: postfix.qemails
   every: 10s
    calc: $emails
    warn: $this > 20
    crit: $this > 100
      to: sysadmin
    info: number of emails in the postfix queue

Source:

https://github.com/firehol/netdata/issues/2567