PowerMTA 6.0r6 released | Key Updates Overview
2026/04/29 by Syed Alam.
We are pleased to announce that PowerMTA 6.0r6 was released. This latest PowerMTA release introduces a number of enhancements, particularly around queue management, routing flexibility, and operational visibility. It brings a lot of advanced features, which keep PowerMTA among the leading MTAs in the market.
You will need a PowerMTA 6.0 license with an active support subscription to run the software. If you do not have a 6.0 license, please contact us for information on updating your license.
Key Updates Overview
Queue Management & Delivery Control
This release brings more granular control over how queues are handled based on SMTP responses.
- It is now possible to take multiple actions within smtp-pattern-list, including rerouting traffic between VMTAs based on specific SMTP replies, instead of only deferring messages.
- Deferrals can now be applied at recipient level based on the actual response, rather than applying broad rules across an entire provider.
- Actions can also be enforced at the queue level, not just per message, allowing more consistent handling of delivery scenarios.
One notable improvement is the ability to treat certain 5xx responses as transient failures, allowing retries instead of immediate bounces.
This is particularly useful for handling Microsoft-related authentication issues, where responses may not always represent permanent failures. In our testing, this approach has significantly improved delivery outcomes.
Additionally:
- Improved support for more complex rerouting scenarios, including cases where queues are rerouted multiple times.
- mx-rollup-list enhancements now allow consolidation of queues based on destination IP or CIDR, helping reduce queue fragmentation..
Administration & Access Control
- A new pmta reroute command allows bulk rerouting of queues (including those created via rollup-by-ip), making operational adjustments easier.
- The web console now supports authentication-based access control, removing the previous limitation of IP-only restrictions.
Troubleshooting & Observability
Several updates make debugging and monitoring more effective:
- DKIM domain and selector information can now be logged, improving visibility into signing behaviour.
- Logging can now be enabled at the job level, instead of the entire queue, reducing unnecessary overhead.
- Enhanced logging for http-webhook helps diagnose connectivity and TLS-related issues more easily.
Other Improvements
- Added support for HTTP CONNECT proxy, client certificate authentication, and TLS CA configuration for Vault integration.
- Fixed a rare DNS resolver issue that could cause delivery to stall.
- Various smaller fixes and performance improvements.
We can also help you upgrade to PowerMTA 6.0 or tune your PowerMTA infrastructure, please contact us for any questions.
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