Sample Powermta Configuration File Hot ((full)) -

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

domain throt-yahoo.com { domain yahoo.com domain yahoo.co.uk max-smtp-out 30 # Yahoo is strict max-per-host-out 30 max-msg-rate 100/hour }

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

log-acct { file /var/log/pmta/acct.csv records "date,time,dsn,vmta,from_addr,to_addr,size" keep 30 }

# ------------------------------------------------------------ # 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

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:

domain throt-microsoft.com { domain outlook.com domain hotmail.com domain live.com max-smtp-out 40 max-per-host-out 40 max-msg-rate 150/hour warmup { period 10 days start-rate 30/hour end-rate 4000/hour } } stress-test with a small warmup list:

/usr/sbin/pmta check config /etc/pmta/config Then, stress-test with a small warmup list: