On Thu, Apr 30, 2015 at 09:26:11AM -0400, James B. Byrne wrote:
> > The fact that the same name fails HELO checks (which don't use the
> > default suffixes) is not unexpected.
> >
>
> Actually, my suspicion was that this was a case of cause and effect.
Your instinct is wrong, and further effort in this direction is
unwarranted.
The Postfix SMTP server smtpd(8), uses getnameinfo() and getaddrinfo()
to resolve the incoming client network address to a hostname and
to chech the validity that hostname. This code does not tweak the
DNS resolver options and is subject to the default DNS search list
from /etc/resolv.conf.
Separately, various restrictions like "reject_unknown_helo_hostname"
and "reject_unknown_sender_domain", ... use explicit DNS lookups
that do disable the search list.
Nothing to see here, the DNS queries are not unexpected.
--
Viktor.
