blocks to map specific sending IPs to logical pools. This allows you to isolate different traffic types (e.g., transactional vs. promotional) and apply unique throttling rules. Authentication Protocols : Modern deliverability is impossible without
By setting these at the global, domain, and vMTA levels, you create a granular control system. For example, you can limit gmail.com to 2000 messages per hour while allowing a more permissive 5000/hour for other, less restrictive domains. This prevents your server from overwhelming any single ISP's mail exchangers and getting temporarily blocked. A common "hot" trick for Microsoft properties (like Hotmail and Outlook) is to use a domain macro to direct them into a single queue, applying one throttling rule to all of them combined.
Below is a complete, production-ready sample PowerMTA configuration file optimized for hot IPs, followed by a detailed breakdown of critical directives. Complete Sample PowerMTA Configuration File sample powermta configuration file hot
# ========================================================== # PowerMTA Hot Configuration Sample (2026) # ========================================================== # -- Global Settings -- http-access 127.0.0.1 admin http-access YOUR_SERVER_IP admin # Replace with your local IP for GUI access http-port 8080 # Define the server hostname host-name mta.yourdomain.com postmaster admin@yourdomain.com # -- Authentication & Security -- domain-key *, *, /etc/pmta/dkim.key # -- IP Rotation/Virtual MTAs (Example: 3 IPs) -- smtp-source-host 1.1.1.1 mta1.yourdomain.com smtp-source-host 1.1.1.2 mta2.yourdomain.com smtp-source-host 1.1.1.3 mta3.yourdomain.com # -- High Throughput Rules (The "Hot" Part) -- max-smtp-out 500 # Increase per destination domain max-msg-per-connection 1000 # Higher number = less reconnection max-conn-rate 10/s # Aggressive connection rate connect-timeout 30s smtp-source-host 1.1.1.1 # Default sending IP dkim-sign yes enable-starttls yes require-starttls no # -- Gmail Aggressive Handling (Keep it warm) -- max-smtp-out 100 max-msg-per-connection 100 max-conn-rate 5/s # -- SMTP Users (For MailWizz/Oempro) -- password your_strong_password source pmta-auth1 always-allow-relaying yes process-x-virtual-mta yes default-virtual-mta mta-pool # Use the pool defined above add-received-header false hide-message-source true # -- Accounting & Logs (Keep minimal for performance) -- log-connections no log-commands no log-data no # log-file /var/log/pmta/log # Only uncomment for debugging accounting-file /var/log/pmta/acct.csv accounting-interval 15m Use code with caution. Copied to clipboard Key "Hot" Configuration Components
Access it via http://YOUR_IP:8080 to track live delivery. blocks to map specific sending IPs to logical pools
<source 0/0> log-connections no smtp-service yes always-allow-api-submission yes default-virtual-mta mta-pool </source>
# Retry logic (Backoff) retry-after 5m
When your IP addresses and domains are fully warmed up, your PowerMTA (PMTA) configuration needs to shift from restrictive throttling to high-performance throughput. A "hot" configuration maximizes delivery speeds while maintaining strict compliance with ISP guidelines to protect your sender reputation.
The sample configuration includes numerous directives that control the rate of sending. These are the primary "hot" levers for controlling throughput and avoiding ISP throttling. The key directives are: A common "hot" trick for Microsoft properties (like
# Global settings server_name = "example.com" server_domain = "example.com"