Wietse Venema via Postfix-users:
> Viktor Dukhovni via Postfix-users:
> > On Tue, Oct 03, 2023 at 06:29:08PM -0400, Wietse Venema via Postfix-users
> > wrote:
> >
> > > > My first wild guess is setting in_flow_delay to a higher value might
> > > > help. Note this may be completely inappropriate for your specific
> > > > application.
> > > > http://www.postfix.org/postconf.5.html#in_flow_delay
> > >
> > > That, and reducinig the number of smtpd processes if the sender makes
> > > parallel connections.
> >
> > When senders chronically exceed the available output bandwidth, rate
> > limits don't help. They just create massive blockages upstream, that
> > will eventually cause large problems.
> >
> > The only solution is to reduce the actual volume of messages originated,
> > or to be able to identify inadvertent floods, and park most of the
> > flood in a short-term quarantine (to be deleted after a sanity check).
> >
> > The job is to identify the root cause, and adress that.
>
> The mail comes from internal IT apps. Passive throttling in Postfix
> (process limit, in flow delay) are options to slow down the flow
> without rejecting mail outright, as with anvil rate limits.
A more structural solution could be to spin up a Postfix instance
(on a separate IP address) for the IT apps, so that their mail
does not compete with other mail.
Wietse
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