Powermta Configuration Guide Top _verified_

Configure the to route these structured logs back to your application.

Add the following directives to your config and restart PowerMTA:

<domain gmail.com> max-msg-per-hour 200000 # Respect Gmail's limits max-msg-rate 50/second # Slower warmup dns-timeout 45 use-starttls yes # Always TLS if available </domain>

<domain yourdomain.com> # DKIM sign-dkim yes dkim-identity "default" dkim-signature-header "v=1; a=rsa-sha256; d=yourdomain.com; s=mail; c=relaxed/simple;" dkim-private-key-file /etc/pmta/dkim/mail.private.key # SPF is set in DNS, but you must use matching envelope-from return-path "bounce@yourdomain.com" powermta configuration guide top

Major inbox providers like Gmail and Yahoo enforce strict authentication requirements. PowerMTA can sign your outbound messages with DomainKeys Identified Mail (DKIM) automatically.

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smtp-source-ip 192.0.2.5 host-name ://yourdomain.com smtp-source-ip 192.0.2.6 host-name ://yourdomain.com Use code with caution. Organizing VMTA Pools Configure the to route these structured logs back

# Main configuration file: /etc/pmta/config # Maximize concurrent connections globally max-msg-rate 0 # 0 means unlimited, controlled per domain max-smtp-out 1000 # Total maximum simultaneous outbound connections # Thread management delivery-threads 50 # Number of CPU threads dedicated to delivery Use code with caution. Queue Management

For senders processing millions of messages per hour, a single PowerMTA node quickly becomes a single point of failure. A two‑tier architecture is the standard pattern:

Set low max-msg-rate values initially for new IPs to build reputation. Related search suggestions provided

Configure PowerMTA to optimize performance and delivery:

: Control who can submit mail to your PMTA. Restrict relaying to local or specific IP addresses to prevent becoming an open relay. > always-allow-relaying yes

# Use multiple disk paths if available spool /var/spool/pmta Use code with caution. Memory and Thread Allocations

PowerMTA also supports directives, allowing you to split large configurations into manageable parts (e.g., one file for DKIM keys, another for ISP‑specific domain rules). This also facilitates the DRY (Don’t Repeat Yourself) principle, which is an official best practice for PowerMTA maintenance.

Grouping IPs allows PowerMTA to automatically load-balance traffic across multiple addresses.