| Directive | Description | |-----------|-------------| | postmaster | Email address for the mailer administrator | | host-name | The hostname PMTA advertises in SMTP | | smtp-listener | Defines on which IP/port PMTA listens for incoming SMTP traffic | | source | Defines where incoming messages are accepted (e.g., from localhost, from a web app) | | virtual-mta | Creates a virtual MTA with its own IP pool and sending behavior | | domain | Applies settings (throttling, DKIM) to specific destination domains | | max-msg-rate | Hourly sending limit per domain, source, or vMTA | | dkim-sign | Enables DKIM signing for outgoing messages | | domain-key | Specifies the path to the DKIM private key for a domain | | http-access | Grants access to the web monitor (critical for remote management) | | log-file | Location of the PMTA log file | | run-as-user / run-as-group | For dropping privileges after startup |
Use max-msg-rate to control email flow. This directive is , so it must be placed inside a <domain> block (or use <domain *> for a global default).
: Controls who can send through your server and their permissions, such as always-allow-relaying .
pmtad --debug
Crucial for maintaining IP reputation by preventing "blasting" that triggers ISP spam filters. max-msg-rate : Limits messages per minute or hour.
smtp-service 25 max-message-size 10M max-recipients-per-message 100 end
The configuration is typically organized into functional blocks: Listener and Source Settings: powermta config file link
# Individual Virtual MTA Definitions smtp-source-ip 192.0.2.1 host-name ://yourdomain.com smtp-source-ip 192.0.2.2 host-name ://yourdomain.com # Linking individual VMTAs into a single, load-balanced pool virtual-mta vmta_ip1 virtual-mta vmta_ip2 Use code with caution. 3. Production-Ready Configuration Blueprint
smtp-source-ip 192.168.1.10 host-name ://yourdomain.com smtp-source-ip 192.168.1.11 host-name ://yourdomain.com Use code with caution. 4. Domain Rules (Throttling and Rate Limiting)
Thus, you can think of a as any way your main configuration references external resources or is assembled from modular components. pmtad --debug Crucial for maintaining IP reputation by
The is typically located at /etc/pmta/config . It is a simple UTF-8 encoded text file that defines how the server listens for, processes, and delivers email. 1. File Structure and Syntax
# --- Global Default Domain Rules --- max-smtp-out 20 # Max parallel connections globally per domain max-msg-per-connection 100 # Recycle connections after 100 emails retry-interval 30m # Retry deferred mail every 30 minutes # --- ISP-Specific Adjustments --- # Gmail Traffic Rules max-smtp-out 50 max-msg-per-connection 500 smtp-4xx-expiry 2d # Drop dead mail faster to save queue space # Yahoo / AOL Traffic Rules max-smtp-out 30 max-msg-per-connection 40 backoff-to-normal-after 1h Use code with caution. 5. Validation and Deployment Workflow