From postfix-users  Tue Sep 17 08:40:05 2019
From: "Helmut Schneider" <jumper99 () gmx ! de>
Date: Tue, 17 Sep 2019 08:40:05 +0000
To: postfix-users
Subject: Re: Change status code for "Host not found"
Message-Id: <xn0lz17uq48p3qq002 () news ! gmane ! org>
X-MARC-Message: https://marc.info/?l=postfix-users&m=156870966501780

Wietse Venema wrote:

> Helmut Schneider:
> [ Charset ISO-8859-1 converted... ]
> > Hi,
> > 
> > I'm running postfix as a relay connected via VPN. If the VPN is down
> > mails are rejected:
> > 
> > relay=none, delay=0.09, delays=0.06/0.02/0.01/0, dsn=5.4.4,
> > status=bounced (Host or domain name not found. Name service error
> > for name=EXCHANGE01 type=AAAA: Host not found)
> 
> It's status=bounced (dsn=5.4.4) because Postfix received a DNS
> NXDOMAIN (name does not exist) response for the name 'EXCHANGE01'.
> 
> > Is there a way to change the dsn to 4xx and deliver it when the VPN
> > is up again?
> 
> http://www.postfix.org/postconf.5.html#default_delivery_status_filter
> Look under the examples for smtp_delivery_status_filter. Here is
> an untested variant that should work.
> 
> /etc/postfix/main.cf:
>    smtp_delivery_status_filter = pcre:/etc/postfix/smtp_dsn_filter
> 
> /etc/postfix/smtp_dsn_filter:
>     /^5(\.\d+\.\d+ Name service error for name=EXCHANGE01/ 4$1

Works like a charm, thank you!