Sample Powermta Configuration File Hot [2021] Guide

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 }

dkim-signature warmup { domain yourwarmupdomain.com selector feb2025 private-key-file /etc/pmta/dkim/warmup.pem } Route outbound mail based on recipient domain. source { default-domain * use-vmta main-sender domain google.com use-vmta warmup-sender domain yahoo.com use-vmta warmup-sender } ---------- RELAY / NAT LOOPBACK ---------- For internal MUA or API submission. relay { listen 127.0.0.1:2525 auth plain auth-login auth-secret /etc/pmta/auth.secret allow-mail-from *@yourmaindomain.com allow-recipient @ route-to-vmta main-sender } Breaking Down the "Hot" Parameters 1. Connection Tuning ( max-per-host-out , max-smtp-out ) The hottest change from defaults: max-per-host-out 100 . Standard config uses 20. Bumping to 100 allows simultaneous delivery to large ISPs like Gmail. However, never exceed 200—Google’s postmaster guidelines suggest 100-120 per IP. 2. Warmup Schedules (Built-in) The warmup { } block inside domain directives is a game-changer. Instead of manually raising limits, PowerMTA automatically increases max-msg-rate over 7-10 days. This prevents ISPs from throttling you as a "sudden burst" sender. 3. Virtual MTA Pools with Source Hashing source-hash true ensures the same recipient domain always uses the same source IP. This is critical for maintaining reputation. Without hashing, rotating IPs randomly can cause ISPs to see "new" IPs for known recipients, triggering spam filters. 4. Logging to RAM Disk (Hidden Hot Trick) The config references /var/log/pmta . In a truly hot system, you should: sample powermta configuration file hot

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

adaptive-throttle { enabled true min-rate 10/hour max-rate 10000/hour step-up-interval 300 } If you have PMTA in two regions, use: Connection Tuning ( max-per-host-out , max-smtp-out ) The

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 } }