<domain *> retry-after 5m # After 1 hour, increase delay retry-after-max 4h # Stop retrying hard bounces after 2 days max-retries 48 </domain>
# Virtual MTA 1: Warm, low-volume (Transactional) <virtual-mta vmta-transactional> smtp-source-host 192.168.1.10 192.168.1.11 max-smtp-out 10 throttle-smtp-out 5 dns-timeout 10 </virtual-mta>
Isolate traffic types (e.g., marketing vs transactional). powermta configuration guide
Implement message age limits:
# Process transient failures separately <domain *> transient-failure-interval 15m # Move to dead queue after 8 hours of temp fails dead-queue-after 8h </domain> <domain *> retry-after 5m # After 1 hour,
Define which IPs PMTA will use to send mail.
: Linux is preferred, specifically stable versions like CentOS 7/8 or Ubuntu 20.04/22.04 . PowerMTA (PMTA) Configuration Guide is a critical feature
PowerMTA (PMTA) Configuration Guide is a critical feature for high-volume senders, focusing on the file (typically located at /etc/pmta/config ) to manage deliverability, security, and ISP compliance. Postmastery 1. Basic Server Setup Virtual MTA Definition
: Ensure your sending IP has a PTR record that matches your sending domain to avoid spam flags. Postmastery 3. Traffic & Throttling Control PowerMTA SMTP | Ultimate Email Server for Bulk Campaigns