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Knowledge base

PMTA knowledge base›Block <inline-seeding>›Directive§ 11.2.2.2.3

eligibility-ttl

<inline-seeding>

How long to remember whether a job is eligible for seeding
in the configuration this is a lineeligibility-ttl 5minside the block <inline-seeding>
A cache of the decision whether to seed

The service decides whether a job is eligible for seeding, and the node remembers that decision — so as not to ask again for every message. The line sets how long it is kept. The default is 5m, the allowed range is from five minutes to an hour.

Increasing it is safe where the setting rarely changes — the vendor says so directly. The price of increasing it is delay: an edit in the vendor’s account will reach the node no sooner than the term expires.

This is a cache of a decision, not a cache of data. The seed assignments themselves are refreshed on a different schedule — batch-frequency.

The main trap is an hour during break-in. You enable seeding for a campaign in the account, and the node keeps considering it ineligible for up to an hour. It is easy to mistake this for a non-working mechanism.
What the Hub does. It does not write it: we do not use the vendor’s seeding — it requires a paid subscription to its tool and an account with the feature enabled.

🔎 The task is close to ours. Seed mailboxes — what we were going to use to measure inbox placement — are solved here by the vendor: addresses are inserted into the mailing automatically, and the results are viewed in its own tool. Our analysis showed that doing it ourselves runs into proxies: polling mailboxes from a single address ends with them being blocked.

Recommended values

The value is chosen by the size and duration of mailings:

Value When
5m (default) the setting is being changed, break-in is under way
1h the setting has settled and rarely changes
The 5m default, the range and the advice to increase it when the setting rarely changes come from the manual (§ 11.2.2.2.3).
Example configuration
<inline-seeding>
    api-key 0123456789abcdef012345678901234567890123
    eligibility-ttl 1h</inline-seeding>
During break-in it is better to keep the default: otherwise edits in the vendor’s account take up to an hour to reach the node.
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 ends2 mistakes▶

Setting an hour during configuration

our experience

What it costsAn edit in the vendor’s account takes up to an hour to reach the node. The mechanism looks non-working.
How to spot itThe campaign was enabled in the account, seeds do not appear.
How to do it rightKeep the default during break-in, raise it afterwards.

Expecting seeding without a subscription to the vendor's tool

§ 11.2

What it costsThe mechanism requires an account with the feature enabled and paid access to the deliverability tool. Without that, a key cannot be created, and so seeding cannot be enabled.
How to spot itThe block is configured, but seeds do not appear in mailings.
How to do it rightCheck the subscription and the key’s rights in the vendor’s account.
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.
Reference data
Syntax
eligibility-ttl <value>
Values
an interval from 5m to 1h
Default
5m § 11.2.2.2.3
Applying
reload, no restart needed
Queue
will not touch what is already queued
Where to write it
<inline-seeding>
How many times
once in the block
Everything here comes from the manual, with the section.
Inheritance
No inheritance: the line lives inside <inline-seeding>, and there is only one such block on a node. Enabling seeding per stream is configured not here but with the enable-inline-seeding line with three levels.
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Related directives

1 relation

Works together with

batch-frequency<inline-seeding>A different cache: this one keeps the eligibility decision, that one — the reconciliation schedule. § 11.2.2.2.4

How to check on the node
Requests to the service for the eligibility flag are visible in the log:
grep -i "eligib\|seed" /var/log/pmta/log | tail -20
The gaps between requests for one job should match the term.
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What else to read

2 articles

◇Seeding campaigns with control addressesThe engine mixes the vendor’s addresses into a mailing, and the result is viewed in the vendor’s deliverability tool; independent of event export.◇Job headerThe x-job header tags a message with a job; the node reads it only if the source is allowed process-x-job, and then the job is visible in accounting, the monitor and pause commands.

In the Hub
Cost of a mistake
safe: a wrong value breaks nothing
Scenarios
Seeding and seed mailboxes
Neighboring settings of the block <inline-seeding>:batch-frequencypersist-thresholdretain-x-sp-subaccount-idprocess-x-sp-subaccount-idapi-keyAll 6 directives of the block →