Sample Powermta Configuration File Hot -

mount -t tmpfs -o size=2G tmpfs /var/log/pmta This prevents log writes from blocking the SMTP pipeline. Use a cron job to flush logs to persistent storage every hour. Before deploying to production, validate the config:

adaptive-throttle { enabled true min-rate 10/hour max-rate 10000/hour step-up-interval 300 } If you have PMTA in two regions, use: sample powermta configuration file hot

vmta warmup-sender { auto-warmup true pool pool-warmup dkim-signature "warmup" max-smtp-out 50 warmup-period 7 days } Sign all outbound mail with DomainKeys. dkim-signature main { domain yourmaindomain.com selector jan2025 private-key-file /etc/pmta/dkim/main.pem header-fields "From:To:Subject:Date:Message-ID" } mount -t tmpfs -o size=2G tmpfs /var/log/pmta This

Introduction: What Makes a PowerMTA Config "Hot"? In the world of high-volume email delivery, PowerMTA (PMTA) by SparkPost is the gold standard for MTA (Mail Transfer Agent) software. However, a standard, out-of-the-box configuration will not survive a modern sending environment. To handle millions of emails per hour, you need a "hot" configuration file —one that is aggressively tuned for throughput, DKIM signing, bounce handling, and ISP throttling. dkim-signature main { domain yourmaindomain

domain throt-aol.com { domain aol.com max-smtp-out 20 max-per-host-out 20 } Distribute load across multiple IPs with source hashing. vmta pool-high-volume { source-hash true # Keep same IP per recipient (affinity) max-msg-rate 10000/minute bind-ip-range 192.0.2.10-192.0.2.30 # Your IPs }

# ------------------------------------------------------------ # PowerMTA Hot Configuration File v4.5+ # Optimized for: 500k - 2M emails/hour # Key features: Multi-IP warmup, ISP throttling, DKIM, Feedback Loop # ------------------------------------------------------------ These set the base behavior for all domains. smtp-service { max-message-size 50M max-connections 5000 max-clients 5000 max-data-connections 2000 connection-backlog 500 tcp-nodelay true tcp-keepalive true dns-timeout 30 dns-retries 2 } ---------- PERFORMANCE TUNING (HOT) ---------- Increase concurrency and reduce latency. processes 8 # One per CPU core max-smtp-out 2000 # Total outgoing connections max-errors-per-domain 20 max-errors-per-ip 10 max-no-answer 10 max-unknown-domain 5 max-per-host-out 100 # High concurrency per ISP max-per-ip-out 240 # Aggressive IP usage queue-retry-period 600 max-queue-size 5M max-retries 48 max-retry-interval 14400 # 4 hours max retry retry-interval 900 # Start retry after 15 min vmta-expansion true vmta-pool-expansion true ---------- BOUNCE & FEEDBACK PROCESSING ---------- Hot config = fast bounce classification. bounce { dsn-retries 5 dsn-wait 3600 lazy-bounce-interval 3600 max-bounce-rate 10% bounce-catcher <bounces@yourdomain.com> }

route backup-dc { destination 203.0.113.5:2525 backup true priority 10 } Before sending real campaigns, use: