We have noticed in our Postfix log a lot of "Temporary lookup failure" error.
They seem to appear randomly as we can't find a pattern.
These errors did happen on well-known domains like
gmail.com so it shouldn't be related to DNS issue.
Here's how it looks like:
Dec 16 02:44:15 prod2 postfix/smtpd[15673]: NOQUEUE: reject:
RCPT from
mx1.example.com[1.2.3.4]: 451 4.3.0 <
exa...@gmail.com>:
Temporary lookup failure; from=<
transa...@example.com>
to=<
exa...@gmail.com> proto=ESMTP helo=<[172.17.0.7]>
We don't have any clue so far so any idea on what might go wrong is helpful! Thanks.