<log debug> file /var/log/pmta/debug.log rotate 1d max-size 500M level 3 </log>

The <source> block is a critical part of the configuration that is often overlooked. It defines which IP addresses (or CIDR ranges) are allowed to connect to your PowerMTA instance to submit mail. The sample config shows a secure setup:

<virtual-mta-pool mta-pool> virtual-mta vmta-hot-1 virtual-mta vmta-hot-2 virtual-mta vmta-warm-1 virtual-mta vmta-warm-2 distribution-rule round-robin-by-domain </virtual-mta-pool>

<domain outlook.com> max-smtp-out 10 require-starttls yes max-msg-rate 150/hour </domain>

To maintain a "hot" yet safe sending environment, you must implement granular rate limiting for specific domains. A common strategy involves setting a conservative global default while allowing higher throughput for trusted domains. Sample Value max-msg-rate Limits total messages per minute/hour max-conn-rate Limits new connection attempts per minute max-smtp-out Maximum concurrent outbound connections max-msg-per-connection Messages sent before closing a session Specialized Domain Handling

domain throt-aol.com domain aol.com max-smtp-out 20 max-per-host-out 20

This sample configuration should serve as a solid, secure foundation that you can customize for your own sending policies and deliverability strategy. The most effective PowerMTA configuration is one that is constantly monitored and tuned based on real-world feedback.

# Logging settings log_level = "info" log_file = "/var/log/powermta.log"