If you have the PowerMTA web UI enabled, you can access domain-specific queue data by crafting a specific URL to fetch JSON data: https://yourserverhostname:8080/domains?format=json This endpoint will provide a structured output containing each domain's name ( name ) and its current queue size ( queue_size ).

Several tools can be employed for monitoring PowermTA: powermta monitoring

This is your Swiss Army knife.

Your queue is the heartbeat of PMTA. A growing queue isn’t always bad—deferrals happen—but a queue that never drains is a warning sign. If you have the PowerMTA web UI enabled,

To truly understand the health of your email infrastructure, you must monitor a range of specific metrics. These can be categorized into delivery, system, and reputation performance.

For those with existing infrastructure monitoring systems (like Nagios, Zabbix, or SolarWinds), PowerMTA also supports SNMP, allowing you to integrate MTA metrics directly into your enterprise dashboard. PowerMTA also supports SNMP

Track 4xx (deferral) and 5xx (denial) codes. Patterns here tell you exactly why Gmail or Outlook is rejecting your mail.