OpenDKIM in Postfix multi-instance environment

From: Fabio Sangiovanni <>
Date: Fri, 21 Oct 2011 09:56:58 +0000

Hello list.

I'm running OpenDKIM in a Postfix multi-instance environment, just for
signing outgoing mail coming from other hosts in the network via SMTP. One
of the main requirements is that the network throughput of the server (8
cpu cores, 16GB ram) must be as high as possible, specially in accepting
mail. I've set all the Postfix instances and OpenDKIM to dialog on a
(single) unix socket, in order to avoid tcp stack involvement.

Is my setup correct? Can I improve performances further?
In particular, my questions are:
1) in order to balance the workload, can I rely on OpenDKIM multithread
capabilities or should I launch multiple instances of OpenDKIM (to match
Postfix instances in a 1:1 fashion, with multiple unix sockets for
2) are there particular settings that impact on signing performances,
beside hash calculation?
3) is there a way to control OpenDKIM thread management? What is the
default behavior about the number of children spawned by the main

Thanks a lot,
Fabio Sangiovanni
Received on Fri Oct 21 2011 - 10:05:31 PST

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