> On 21 Nov 2020, at 15:53, Wietse Venema <wie...@porcupine.org> wrote:
>
> Gerben Wierda:
>> I think I am using postfix defaults here.
>>
>> WHen a client is rejected because of a mssing reverse hostname, I see:
>>
>> Nov 21 15:37:02 mail smtp/smtpd[2168]: NOQUEUE: reject: RCPT from
>> unknown[46.221.40.2]: 450 4.7.1 Client host rejected: cannot find your
>> reverse hostname, [46.221.40.2]; from=<a95901...@rna.nl>
>> to=<a95901...@rna.nl> proto=ESMTP helo=<[46.221.40.2]>
>>
>> And I was just wondering: why is that a 4xx message (temp failure) and not a
>> 5xx failure?
>
> Postfix WILL NOT report a DNS 'try again' error as a hard error.
> Gmail used to make that mistake with their IPv6, causing me
> to disable IPv6 for gmail.
I see! I wasn’t aware that DNS has ’try again’ errors too. Understandable.
Thanks.
G
