Aaron Bennett:
> Hi,
>
> For reasons beyond my control, one of the hosts we need to relay
> to is occasionally dropping out of dns. We relay to it based on
> an ldap map which returns:
>
> relay:[office365relay.clarku.edu]
>
> That host is a CNAME for an external vendor. It's not hard to guess which
> one.
>
> When it drops out, the message bounces:
> Jan 8 13:50:28 mothra.clarku.edu postfix/smtp[27291]: E1614684CCD:
> to=<u...@clarku.edu>, relay=none, delay=0.18, delays=0.06/0.03/0.1/0,
> dsn=5.4.4, status=bounced (Host or domain name not found. Name
> service error for name=office365relay.clarku.edu type=A: Host not
> found)
>
> I'd prefer it to defer. I'm not sure why it's not deferring - is
> it the relay: line, or the [] enclosure, or something else?
Postfix would defer when it receives no DNS reply.
Postfix bounces because the DNS server replies that this DNS
record DOES NOT EXIST.
To work around, use soft_bounce=yes and watch your queue
carefully for mail piling up.
Wietse
