# Inside /etc/pmta/pmta.config
include /etc/pmta/sources/isp-aol.conf
include /etc/pmta/sources/isp-gmail.conf
include /etc/pmta/domains/my-virtual-domains.conf
One of the most powerful aspects of linking in PowerMTA is the override chain. If the same configuration parameter appears in multiple linked files, the last parsed instance generally takes precedence, following the order of includes.
| Issue | Detail |
|-------|--------|
| Circular includes | PowerMTA detects and rejects them at parse time. |
| Order sensitivity | Overrides depend on include order. Explicit ordering (prefix numbers) is recommended. |
| Reload behavior | Changing an included file requires pmta reload to take effect. |
| Permissions | All included files must be readable by the user running PMTA (usually pmta). |
The SMTP settings section configures PowerMTA's behavior as an SMTP server. Some key parameters include: powermta config file link
Example:
smtp_port = 25;
smtp_auth = true;
allowed_senders = ["127.0.0.1", "192.168.1.0/24"];
Here is the trap: The license file is cryptographically linked to your server’s hostname and MAC address. If you change your network interface or clone a VM, the license link "breaks." PowerMTA will fall back to a 5,000 email/hour throttle. # Inside /etc/pmta/pmta
Troubleshooting the license link:
PowerMTA’s main configuration file (commonly named pmta.conf) defines domains, IPs, delivery rules, logging, bounce handling, rate limits, DKIM/SPF, TLS, and other MTA behavior. One of the most powerful aspects of linking
PowerMTA is proprietary software from SparkPost (formerly Port25). You typically get access to the full config reference and examples after purchasing a license.
However, here are the most useful official links:
