Edgar Fu?:
> > Postfix tries ALL CONFIGURED ADDRESS TYPES,
> Your capitalization of "configured address types" seems to imply
> this is a well-defined term in the context of Postfix configuration,
> but sorry, I don't know how it's defined.
Sorry for shouting, I did not have color or underline capabilities.
The configured protocols are specified with the inet_protocols
parameter. For example, my server has both IPv4 and IPv6:
inet_protocols = ipv4, ipv6
> > and when NO CONFIGURED ADDRESS TYPE works
> This seems to imply Postfix tried an A lookup for "smtp" before and that
> failed.
> However, a simple "host smtp" works as expected, so the problem
> must be a bit less obviuos.
The Postfix DNS client no longer appends the default domain. Thus,
a lookup of "smtp" will not look up "smtp.example.com" (if example.com
is your default domain).
> > it logs the LAST ERROR.
> OK, thanks for that explanation.
> What's the suggested method for finding out what's wrong with my
> setup so that the A lookup failed?
Postfix does the equivalent lookups of
host -t mx smtp.
host -t a smtp.
host -t aaaa smtp.
Note the trailing dot.
Postfix skips the MX lookup if the name is enclosed in [].
"smtp" is not a valid top-level domain at this time, so
you would need to specify the full name.
The order of A versus AAAA is Postfix version dependent.
Before Postfix 2.8, the order was AAAA then A.
With Postfix 2.8 the default is "smtp_address_preference=ipv6",
meaning by default look up AAAA before A.
With Postfix 2.9 the default is "smtp_address_preference=any",
meaning by default randomly try AAAA or A first.
I recommend "smtp_address_preference=any" if you have both IPv4 and
IPv6 connectivity. At this time, connectivity can greatly differ
depending on protocol, and making the order random increases the
chances that mail will eventually go through.
Wietse
