> On Jan 4, 2019, at 7:23 AM, Wietse Venema <wie...@porcupine.org> wrote:
>
> For one delivery request, the Postfix SMTP client gets up to
> five ($smtp_mx_address_limit) addresses from DNS, and burns through
> those addresses in a split second as they fail with ECONNREFUSED.
> Instantly, he has used up his entire 5 connections/second budget
> with only one delivert request.
>
> Obviously, the queue scheduler has no idea how many 'connections'
> are being used up per delivery request. No amount of scheduler
> tweaking will change that.
Well for that we have smtp_mx_address_limit, which could be
reduced from 5 to 2 (or perhaps 3). That does risk problems
delivering to sites whose primary MX has multiple IPs and is
fake, with the real MX at worse priority, but such sites clearly
don't really want to receive much mail... :-(
--
Viktor.
