Before making any changes, always create a backup of your working configuration file. PowerMTA requires a service restart or a configuration reload ( pmta reload ) to apply most changes. 2. Essential Top-Level Directives
http-mgmt-port 8080 http-access 127.0.0.1 monitor http-access YOUR_IP_ADDRESS/32 admin
tail -f /var/log/pmta/acct.csv | grep -v "dsn="
PowerMTA reads its configuration in a specific order: powermta configuration guide top
Check /var/log/pmta/log daily for unexpected ISP blocks. To help tailer this setup, let me know: What volume of email do you plan to send daily?
smtp-source-ip 1.2.3.4 host-name mail1.yourdomain.com Use code with caution. 3. Authentication for 2025 Deliverability PowerMTA: Best Solution for High-Volume Email Delivery
Separating traffic into "pools" allows you to isolate different types of mail (e.g., transactional vs. marketing) and assign specific IP addresses to each. : Assign a unique source IP to each. smtp-source-ip 1.2.3.4 Use code with caution. Copied to clipboard Before making any changes, always create a backup
Example: bounce-action permanent action suppress end bounce-action
The /etc/pmta/config file is the single source of truth for PowerMTA. It uses a hierarchical XML‑like structure built from directives .
Ensure always-allow-relaying is restricted to your internal application IPs only, or use SMTP authentication to prevent the server from being an open relay. Configure smtp-listener blocks with require-auth yes and a defined auth-method . Before making any changes
# Backoff Configuration # If we see these errors, slow down backoff-notify Postmaster@yourdomain.com
: smtp-listener 0/0:2525 (Port 2525 is often used for incoming mail from your application).
<http-listener 8080> access-group admin-users # Enable REST API accept-x-mailer-header true </http-listener>
| Parameter | Recommended Value | Why | | :--- | :--- | :--- | | max-smtp-out | 30 (Global), 2-20 (per domain) | Prevents local resource exhaustion | | smtp-out-connection-timeout | 60s | Drop dead connections fast | | smtp-out-data-timeout | 180s | Allow large attachments but don't wait forever | | queue-sync-interval | 10 | Flush metadata to disk frequently | | max-recipients-per-message | 100 | Avoids fragmentation on big ESPs |
<virtual-mta vmta-pool> smtp-source-host 192.168.1.10 smtp-source-host 192.168.1.11 smtp-source-host 192.168.1.12 smtp-mail-host mail.mydomain.com max-smtp-out 30 domain-key default,mydomain.com,/etc/pmta/dkim/private.key </virtual-mta>