Crucial for maintaining IP reputation by preventing "blasting" that triggers ISP spam filters. max-msg-rate : Limits messages per minute or hour.
<virtual-mta marketing> smtp-source-host 192.168.1.10 marketing.yourdomain.com max-msg-rate 5000/h </virtual-mta>
You must have root or sudo privileges to edit this file. If you are setting up a new instance and looking for a foundational template, the official PowerMTA configuration documentation is the primary source, but a basic structure is included below. 2. Basic PowerMTA Config File Structure
A production-grade PowerMTA setup typically utilizes a modular file linking system. Below is the industry-standard blueprint for structuring your links.
Once you've made your changes, you need to make PowerMTA aware of them. The recommended method is to perform a ( pmta reload ), which applies most changes dynamically without interrupting service. For changes that aren't dynamically reloadable (like spool directory locations), a restart ( systemctl restart pmta ) is required. powermta config file link
If the terminal returns no errors, your configuration file and all its linked sub-files are structurally sound. Step 2: Reload the Configuration
This directive is the entry point for all mail. It defines which IP addresses and ports PowerMTA should listen on for incoming SMTP connections.
The main sections of the PowerMTA config file include:
/etc/pmta/license (Must be present for the service to start) If you are setting up a new instance
The delivery settings section controls how PowerMTA delivers email to recipients. Some important parameters include:
Use a cron job or a webhook on your PMTA servers to pull updates automatically.
A production-ready configuration file relies on structured blocks called "directives." Below are the essential components you must link and configure. 1. Global Settings
</virtual-mta>
always-allow-relaying yes smtp-users-authentication no auth-type password allow-starttls yes Use code with caution. 3. Virtual MTAs (Outbound IPs)
PowerMTA Config File Link: The Ultimate Guide to Configuration and Optimization (2026)
############################################################################ # BEGIN: GENERAL OPTIONS ############################ How To Install Powermta On Centos 7 | by Vikash nehra
If the syntax is valid, reload the configuration without stopping the PowerMTA service: pmtcmd reload Use code with caution. Learn More Virtual MTAs ( )
#--- PowerMTA Configuration File ---# # 1. Basic Server Settings http-mgmt-port 8080 http-mgmt-password yourSecurePassword123! log-file /var/log/pmta/pmta.log acct-file /var/log/pmta/acct.csv # 2. SMTP Listening Settings (Inbound) smtp-listener 0.0.0.0:25 # 3. Virtual MTAs (Outgoing IPs) smtp-source-ip 192.0.2.1 hostname ://example.com smtp-source-ip 192.0.2.2 hostname ://example.com # 4. Virtual MTA Pools (Grouping) virtual-mta vmta1 virtual-mta vmta2 # 5. Domain Specific Settings (Deliverability) max-smtp-out 20 retry-after 5m dkim-sign true dkim-key-selector selector1 dkim-key-file /etc/pmta/dkim/selector1.pem # 6. Security & Authentication smtp-server-tls-certificate /etc/pmta/tls/server.crt smtp-server-tls-private-key /etc/pmta/tls/server.key smtp-server-tls-enable true # 7. Allowed Sources (Who can send through this PMTA?) password your_smtp_password Use code with caution. Key Configuration Directives Explained 1. Virtual MTAs ( )