: Highly sensitive to sudden bursts. The inter-msg-delay 100ms directive forces a tiny pause between messages on a single connection, protecting your IP from spam-filter triggers.
# Web UI access authentication-type basic authentication-file "/etc/pmta/htpasswd"
Use the command pmta debug to check for syntax errors or line number issues before restarting the service. How to Install & Setup PowerMTA on CentOS 7 sample powermta configuration file hot
# Deny relaying from blocked hosts deny relay from "blocked_mta.example.com"
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 : Highly sensitive to sudden bursts
<!-- SMTP LISTENER --> <!-- Listen for incoming mail from your application --> <smtp-listener> <port>25</port> <address>0.0.0.0</address> <max-rate>500/s</max-rate> <!-- Accept mail quickly from local apps --> </smtp-listener>
# ------------------------------------------------------------------ # PowerMTA Configuration File - High Volume (Hot) Setup # ------------------------------------------------------------------ # --- Basic Settings --- # Replace with your actual server hostname smtp-server-hostname ://yourdomain.com http-mgmt-port 8080 http-mgmt-acl 127.0.0.1 192.168.1.0/24 # Allow access only from trusted IPs log-file /var/log/pmta/pmta.log log-rotate 10 10M # --- Source and Security --- # Define authorized IPs that can send through this PMTA server always-allow-relaying yes smtp-service yes process-x-virtual-mta yes # Optional: Authentication (Recommended if public) # auth-clients auth-user-1 # --- DKIM Signing --- # Assuming your domain is yourdomain.com dkim-key /etc/pmta/yourdomain.com.pem dkim-selector selector1 dkim-sign yes # --- Virtual MTAs (IP Pooling) --- # Define Virtual MTAs for different IPs to spread reputation smtp-source-ip 192.0.2.10 # Replace with IP 1 # Example to add dkim to vmtas # dkim-key /etc/pmta/key1.pem # dkim-selector selector1 # dkim-sign yes smtp-source-ip 192.0.2.11 # Replace with IP 2 # Create a pool to use virtual-mta vmta1 virtual-mta vmta2 # --- Domain-Specific Rules (Hot Settings) --- # Default rules for unknown/other domains max-smtp-out 20 max-msg-per-connection 50 max-msg-rate 500/m # Optimized rules for Major ISPs (High Volume) max-smtp-out 50 max-msg-per-connection 100 max-msg-rate 2000/h # Recommended: Use dedicated IP for Gmail # vmta-pool mta-pool1 max-smtp-out 40 max-msg-per-connection 80 max-msg-rate 1500/h max-smtp-out 30 max-msg-per-connection 60 max-msg-rate 1000/h # --- Performance Tuning --- smtp-out-max-concurrency 1000 smtp-out-max-msg-per-connection 100 smtp-out-max-msg-rate 10000/m Use code with caution. Detailed Directive Breakdown 1. virtual-mta & virtual-mta-pool How to Install & Setup PowerMTA on CentOS
virtual-mta vmta-ip-1 smtp-source-host 192.168.1.101 mail1.yourdomain.com
This section defines how your applications or users connect to PowerMTA to send emails.
max-deliveries-per-connection 20 max-delivery-threads 200 max-message-size 52428800 ; 50MB max-queued 200000 log-level info delivery-queue /var/spool/pmta/queue statistics true statistics-file /var/log/pmta/stats.log pid-file /var/run/pmta/pmta.pid