On 2024-10-16 at 09:05:09 UTC-0400 (Wed, 16 Oct 2024 14:05:09 +0100)
Dominic Preston via Postfix-users <lzq...@gmail.com>
is rumored to have said:
When sending email via my email client, there is a delay of about 5
seconds
before the email sends. I believe this is as a result of my ISP's DNS
servers being unresponsive when responding to PTR record lookups for
my
client IP address.
If your rDNS is non-performant or non-existent, you probably should find
a better hosting provider.
However, multi-second delays at connect time are perfectly normal and
intentional in many cases. For example, Postfix's postscreen component
will pause for 7 seconds at connect time in the middle of the intro
banner for IPs that are not in its cache of non-spambot clients.
Is there any way to disable PTR record lookups for a given set of
IPv4/IPv6
addresses?
On other people's mail servers? Not from the machine whose address is
being looked up.
On your own mail server, the canonical mechanism to short-circuit rDNS
lookups is to add entries in the hosts file for the IPs needing the
faster resolution, assuming that you have your system resolver set to
use files first (in /etc/nsswitch.conf)
--
Bill Cole
b...@scconsult.com or billc...@apache.org
(AKA @grumpybozo@toad.social and many *@billmail.scconsult.com
addresses)
Not Currently Available For Hire
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