Re: [exim] Exim and sympa with DSN enabled lists

On 07/07/2022 18:19, Sabahattin Gucukoglu via Exim-users wrote:
> your best option being immediately queueing such messages and then running them from a queue with some limited number of (dynamically or pre-spawned) queue runners at some fixed low interval. (See main options remote_max_parallel and queue_run_max, and SMTP transport option serialize_hosts.) This comes at a regrettable cost to both latency and system load for polling for messages from the queue and starting enough runners to give good performance without abusing hosts

One other point: if your source does dump a lot into the queue in a short
time, best performance will be obtained using 2-phase queue runs (the -qq option).

Exim has always had configurable limits on queue-runner numbers; the standard
method of starting them at fixed intervals result, with a large queue, of
that maximum number being used. There are also per-destination-host limits
(to avoid "abusing hosts").

Futher, from 4.95 onwards, when -qq in used the required number of runners
will be started more quickly when the spool fill is high.
--
Cheers,
Jeremy