On Tue, Mar 10, 2020 at 05:18:01PM -0500, Noel Jones wrote:
> On 3/10/2020 4:55 PM, Stefan Bauer wrote:
> >
> > i know this is quite old, but
> > smtp_fallback_relay should only get triggered on
> > undeliverable-events and not when remote replies with a 4xx or 5xx -
> > right?
Not quite. When a delivery via the primary nexthop tempfails, the
fallback relay is used:
smtp_mx_session_limit (default: 2)
The maximal number of SMTP sessions per delivery request before the
Postfix SMTP client gives up or delivers to a fall-back relay host, or
zero (no limit). This restriction ignores sessions that fail to
complete the SMTP initial handshake (Postfix version 2.2 and earlier)
or that fail to complete the EHLO and TLS handshake (Postfix version
2.3 and later).
With 5xx, of course, the message the message is normally immediately
bounced (modulo soft_bounce and all that).
--
Viktor.
