On Mon, Jun 15, 2020 at 08:25:31PM -0500, Noel Jones wrote:
> Postfix has only one queue, and concurrency and process count is
> per-destination, not based on where the mail came from.
>
> Consider using a separate postfix instance for delivering mail list
> messages to prevent them from interfering with regular mail. See
> MULTI_INSTANCE_README
There's one active queue, but within that active queue messages are
queued to a particular (transport,nexthop) pair, and scheduling is
round-robin by transport, and then FIFO, subject to concurrency and
process limits and amortised preëmption of multi-recipient messages by
messages with fewer recipients, so that messages with lots of recipients
don't hog the queue too long before some other messages with fewer
recipients that arrived later get to use a delivery slot.
If one just wants to put messages in multiple "lines" for delivery
scheduling, but otherwise all settings are the same, then using multiple
transports is simpler and often just as effective as multiple instances.
--
Viktor.
