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Knowledge base

PMTA knowledge base›Configuration block§ 3.3.13

<virtual-mta-pool>

A group of sending addresses
One name instead of a list — and one trap thrown in

The block combines several sending addresses under one name. A message directed to the pool goes out from one of its members — the engine rotates them.

Why this is needed. First, so as not to list addresses in every selection rule: the pool has one name, and members can be added and removed. Second, to spread the flow across several addresses.

🔴 And right away the main subtlety. A setting written in the pool goes to each member rather than being divided among them. A 100/m limit in a pool of five addresses means a hundred for each, that is, five hundred from the pool. This is analyzed on the directives’ own pages and in vmta-pool-semantics.

Example configuration
# the Hub keeps only the member list in the pool
<virtual-mta-pool pmta-pool>
    virtual-mta mta-news-1    virtual-mta mta-news-2
</virtual-mta-pool>
The highlighted line is the only one the Hub writes here. It has no limits or signing keys in the pool: they would go to each member, while warm-up takes addresses through different schedules.
yellow — — directive names, blue — blocks. They are highlighted the same way in the text of the card.
Block directives: 9
Sending addresses 8
virtual-mtacriticalset by the HubA pool member and the share of traffic it getsdomain-keyThe same signing key, declared at the pool levelmax-smtp-msg-rateThe sending rate each address in the pool getsmax-smtp-outThe connection ceiling each address in the pool getssuppression-listsSuppression lists shared by all addresses in the poolinclude-headers-fromA headers file shared by the pool’s addressesmax-smtp-data-volume-rateA byte ceiling that each pool address getsrewrite-listThe rewrite rule list shared by the pool’s addresses
Receiver rules 1
domainA receiver rules block that goes to all pool members
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.
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What else to read

3 articles

◇Accept, route, deliverA message’s path inside the node: accept, decide where, deliver — and all the settings live between these three steps.◇Four value types the whole config is written inBoolean, domain pattern, regular expression and time interval — defined once in § 3.2 and then used by all directives.◇Reloading settings versus restarting the serviceThe configuration is read at startup, and after that edits are picked up by the reload command — except for the directives the manual marks as requiring a restart.

In the Hub
Cost of a mistake
reversible: harms only while it is set
Scenarios
Configuration lifecycle