<domain *>
return-path bounce+%session_binding_domain+%msg_id@bounce.yourdomain.com
</domain>
This encodes binding and message ID into the bounce address for automated processing.
dns-cache-size 10000
dns-timeout 30
dns-retries 2
dns-workers 16
| Mistake | Consequence | Fix |
| :--- | :--- | :--- |
| max-smtp-out 1000 on a 2GB VM | Connection flooding, kernel panic | Set to 250 max for small VMs |
| No domain * block | Wildcard throttling fails | Always define a default domain |
| max-msg-per-connection 0 | Never closes connections | Set to 50-200 |
| Ignoring initial-pts | Getting blocked for "hammering" | Set initial-pts 60 minimum |
| Running as root | Security breach | Use process-user | powermta configuration guide top
Use patterns to delay retries intelligently. This encodes binding and message ID into the
<smtp-pattern 4xx>
pattern ^4[0-9]2
initial-pts 60
max-pts 3600
</smtp-pattern>
PowerMTA (by Port25) is the industry standard for high-volume email delivery. Unlike standard MTAs (Mail Transfer Agents), PowerMTA is built specifically for commercial sending, offering granular control over delivery speed, bounce processing, and reputation management. | Mistake | Consequence | Fix | |
However, installing PowerMTA is only the first step. To maximize inbox placement and throughput, you must configure the config.dat file correctly. This guide covers the top configuration settings you need to master to ensure stability and high deliverability.