Dirk St?cker:
> > With "smtp_address_preference = any", this random sort mixes IPv6
> > and IPv6 addresses with the same MX preference. Otherwise, an IPv4
> > address sorts before or after an IPv6 address with the same MX
> > preference.
>
> Thanks. I thought so, but couldn't find it. Was the postfix 2.8 default
> changed to "any" because there was trouble caused by broken IPv6
> installations (which usually even today nearly nobody notices :-)?
Yes. The old default was "smtp_address_preference = ipv6" (try IPv6
before IPv4 with the same MX preference). Some vendors configured
Postfix to always enable IPv6. That would make some destinations
unreachable for IPv4-only hosts, as Postfix will try only up to
$smtp_mx_address_limit IP addresses.
Wietse
