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PMTA knowledge base›Mechanism§ 1.2

The activation key is a prerequisite for installation, not a step after it

license activation key (LAK)
Not just a pass, but a ceiling

The engine does not start without an activation key, and the key is issued by the vendor’s support. The manual puts it in the list of what must be ready before installation, not in the list of first steps after it.

A license is not just a pass. Its tier limits the configuration: with a standard license the outgoing connection ceiling is always 200, and anything written above that the engine simply ignores. With an enterprise license the default is 1200, and there is no upper limit.

Hence a consequence for anyone reading someone else’s configuration: the written value and the effective one can diverge, and the reason will be not the syntax but the license. The line is there, parsing accepted it, but a different number is in effect.

There is also a second license axis — by sending volume (volume-based-licensing); it works differently and lives in its own chapter.

The main trap is silent ignoring. The manual simply calls a connection ceiling above the license one ignored: the configuration parses, but the number does not apply. A node on a Standard license with fifteen hundred connections written works as if with two hundred, and the analysis of “why sending is slower than calculated” goes anywhere but the license.
What the Hub does. It neither issues nor checks the key — it comes to the client from the vendor and is entered when the engine is installed.

⚠️ The Hub’s presets do not take the license into account. It calculates connection numbers from the rate, not from which license the client has. On a node with a standard license a generous preset will silently hit two hundred connections — the calculated rate will not be reached, and the reason will not show up anywhere except on this page.

The node can check its license tier with its own command; the telemetry the Hub collects does not include this data.

Recommended values

What to know about the license when reading a configuration:

What Standard Enterprise
outbound connection ceiling always 200, above that is ignored 1200 by default, no upper limit
the manual’s advice — no higher than 7500 because of machine and system limits

The first thing to check on an unfamiliar node is not the license tier in the documents but what the engine itself prints: a mismatch between what is written and what applies is explained right here.

Keep the key with the configuration. It is as much a part of the node’s recoverable state as the settings files, and it sits in the same directory: on Linux, /etc/pmta/license.

The advice to check the license tier first is ours. From the manual come the facts that the key is mandatory and obtained from support, the license file path and the connection ceilings of the two license tiers with the caveat that exceeding them is ignored (§ 2, § 2.2, § 3.3.1.2).
Example configuration
# the number in the configuration and the number in effect are different things
total-max-smtp-out 1500
# with a standard license 200 is in effect, and there will be no error
The highlighted line is a comment, not a setting, and that is the point: the engine will say nothing. You can find out that the number is not in effect only by checking the license tier.
yellow — — directive names, blue — blocks. They are highlighted the same way in the text of the card.
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Common mistakes and problems

what people get wrong and how it ends3 mistakes▶

Setting a connection ceiling without checking the license

§ 3.3.1.2

What it costsA standard license always limits outgoing connections to two hundred. Anything written above that is ignored silently — no error, no warning. The calculated rate is not reached, and the reason is visible neither in the configuration nor in the log.
How to spot itThe number of open connections is capped at exactly two hundred, no matter how much you raise the ceiling.
How to do it rightCheck the license tier with the node’s command. On a standard license calculate the rate from two hundred connections, not from the written number.

Leaving the key for “after installation”

§ 1.2

What it costsThe manual puts the key in the list of requirements before installation. Without it the engine does not work, and the prepared machine sits idle while the key is requested from support.
How to spot itInstallation completed, the engine does not start, and there is no key yet.
How to do it rightRequest the key together with preparing the machine, not afterwards.

Not including the key in backups

§ 1.8

What it costsThe key sits in the configuration directory and is part of the node’s state. Restoring without it means a new support request and downtime exactly when the node is needed most.
How to spot itThe node is restored, the configuration is in place, but the engine does not start.
How to do it rightCopy the whole configuration directory — the key is in the same place as everything else.
Compatibility
PowerMTA 6.0
described in the manual of this version · platform: any
The vendor does not state the first version for every directive — there is no note here. The name also appears in the 5.0 edition of the manual.
Inheritance
A license has no inheritance — it is a property of the whole instance. But it puts a ceiling over the node-level total-max-smtp-out directive: that one is not inherited either, and together they form the upper boundary that all connection limits at the receiver and sending address levels run into.
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Related entries

2 relations

Does not work without

Prepare a machine for the engineThe key is listed among the things that must be ready before installation. § 1.2

Affects

total-max-smtp-outGlobalThe directive whose effective value the license cuts — silently. inference

Referenced from

A license for a fleet, not for a serverA related mechanism: they work together. § 2.6License fileThe very key without which the engine does not work — here it is in file form. § 2.2postmasterGlobalThe warning about upcoming license expiration arrives here as well. § 3.3.1.4ConnectionsThe license key also takes part in the ceiling — so the number is limited not only by the configuration. § 5.3

How to check on the node
The license tier and its term are printed by the engine itself:
pmta show license
pmta show status
The first shows the license tier and the key’s term. The second shows the Connections line: the maximum column for outbound is the ceiling in force, whatever number stands in the configuration.
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What else to read

3 articles

◇Cloud restrictionsClouds restrict outbound mail on port 25 until you ask them to lift the limit, and mailbox providers treat their address ranges with suspicion.◇How to turn a sending plan into hardwareTwo constants for sizing any node: about 2 KB of memory per queued recipient and spool space proportional to the total size of the messages.◇A license for a fleet, not for a serverThe license is not bound to a server: it is installed on as many machines as the instance limit allows, and the nodes send volume statistics to the vendor every hour.

In the Hub
Cost of a mistake
safe: a wrong value breaks nothing
Scenarios
Capacity planning · Prepare a node for sending