Powermta Configuration Guide Top

The most powerful feature of PowerMTA is the ability to create VirtualMTAs. These allow you to manage multiple sending domains or clients on a single physical server, isolating their reputations.

<domain gmail.com>
    max-smtp-out 20          # Gmail limits concurrency per IP.
    max-msg-rate 10/s        # Respect Google's rate limits.
    max-msg-per-connection 50
    use-starttls always      # Force TLS for security.
    require-starttls true
    dns-timeout 15s
    initial-pts 30
    max-pts 3600
    pts-expiration 5m
    # Feedback loop support
    dsn true
</domain>

Modern PowerMTA setups often use the HTTP API for better throughput and easier integration than SMTP.

<http-listener 8080>
    access-group admin-users
    # Enable REST API
    accept-x-mailer-header true
</http-listener>
<http-user admin>
    password "encrypted-password-here"
</http-user>

<virtual-mta main> ip 203.0.113.10 ip 203.0.113.11 max-smtp-out 250 max-msg-rate 50/s </virtual-mta> powermta configuration guide top

PowerMTA (Port25) is the industry standard for high-performance email delivery. Unlike standard MTAs (like Postfix or Sendmail), PowerMTA is built specifically for commercial sending, offering granular control over connection handling, throttling, and feedback loops.

However, installing the software is only the first step. A default configuration will rarely yield optimal results. This guide covers the top configuration priorities to transform a basic installation into a deliverability powerhouse. The most powerful feature of PowerMTA is the

Bindings connect a VMTA to a domain with specific rules:

<bind source-vmta="gmail-ip1" destination-domain="gmail.com">
    source-interface 192.0.2.10
    max-smtp-out 20
    max-smtp-out-per-ip 4
    <dkim>
        sign yes
        selector 2024
        domain senderdomain.com
        key-file /etc/pmta/dkim/sender.key
    </dkim>
</bind>
<bind source-vmta="yahoo-ip2" destination-domain="yahoo.com">
source-interface 192.0.2.11
max-smtp-out 15
max-smtp-out-per-ip 3
</bind>
 Modern PowerMTA setups often use the HTTP API

Advanced binding trick – warmup IPs:

<bind source-vmta="warmup-ip1" destination-domain="*">
    source-interface 192.0.2.100
    max-smtp-out 5
    <limits>
        throttle 100/hour
        max-messages-per-connection 10
    </limits>
</bind>