Paul Tomblin via Mailman-users writes:
Right now it appears to be obeying the destination_recipient_limit (5) in my postfix configuration, but it's not obeying the destination_concurrency_limit (1),
Is that a typo? In <https://www.postfix.org/postconf.5.html> I didn't finad a mention of 'destination_concurrency_limit', rather a family of "default_destination_concurrency_limit" and "$TRANSPORT_destination_concurrency_limit" variables for $TRANSPORT = "smtp", "lmtp", "local", etc. (Similarly for "*_destination_recipient_limit".)
Also note that "*_destination_recipient_limit = 1" changes the meaning of the corresponding "*_destination_concurrency_limit" from "per domain" to "per recipient". From what you write above this isn't an issue in your configuration, but remember that "1" is special here.
and hitting their servers with a bunch of connections at the same time. My research into postfix configuration continues.
I wonder if I should set max_recipients to 0 in Mailman, and let Postfix decide how many recipients, if things would be a bit happier?
This is more likely to give you full control over a mail flow than having Mailman decide. In general it's better to configure limits as close to the agents you *don't* control as possible so downstream agents in your system don't mess with it. For example, if you have a set of messages to a site that all have temporarily failed, Postfix will likely batch them up for retry. Mailman can't do anything about that. Also, probably more important from your point of view, is that Postfix can deal with draconian limitations at one recipient domain and be more performant at sane domains. Mailman can't.
Steve
-- GNU Mailman consultant (installation, migration, customization) Sirius Open Source https://www.siriusopensource.com/ Software systems consulting in Europe, North America, and Japan