kumomta/docs/reference/kumo/configure_log_hook.md

kumo.configure_log_hook {PARAMS}

Configures the lua logging hook. When enabled, each matching log event will cause cause new a Message to be generated and have its body assigned to the log record (or to its template expansion if you have configured that), and passed to the should_enqueue_log_record event.

kumo.on('init', function()
  kumo.configure_log_hook {
    headers = { 'Subject', 'X-Customer-ID' },
  }
end)

This allows you to utilize KumoMTA's internal queueing to dispatch log events to external systems such as webhooks or some external queuing system for processing elsewhere in your deployment architecture.

See should_enqueue_log_record for an example.

The following options are configurable for the logging hook and work the same way as their counterparts in local log file logging. Rather than duplicate the information here, this section links to those options:

• back_pressure
• meta
• headers
• per_record

In addition, the following options are supported:

deferred_spool

If set to true, the generated message will not be immediately saved to the spool in the case that your should_enqueue_log_record indicates that the message should be queued.