[pfx] Re: I keep getting disabled on [email protected] mailing list

On 17/06/2026 5:55 am, Patrick Ben Koetter via Postfix-users wrote:
> * Al via Postfix-users <[email protected]>:
>> I have taken a look at my logs:
>> 
>> This is the error:
>> 
>> Jun  9 12:03:41 sequoia postfix/smtpd[52759]: NOQUEUE: reject: RCPT 
>> from
>> unknown[45.90.5.195]: 554 5.7.1 Client host rejected: cannot find your
>> reverse hostname, [45.90.5.195]; 
>> from=<[email protected]>
>> to=<[email protected]> proto=ESMTP helo=<list.sys4.de>
>> 
>> However, most of the of the time it lets, it through:
>> 
>> 0.43, dsn=2.6.0, status=sent (250 2.6.0 <[email protected]> Message 
>> accepted
>> for delivery)
>> Jun 14 06:35:36 sequoia postfix/qmgr[83260]: 4DC2D1F5A07: removed
>> 
>> I added:
>> 
>> [email protected]       OK
> 
> list.sys4.de has valid PTRs for it's A and AAAA record:
> 
> $ dig +short -x 2a03:4000:20:189::195
> list.sys4.de.
> 
> $ dig -x 45.90.5.195
> 
> ; <<>> DiG 9.10.6 <<>> -x 45.90.5.195
> ;; global options: +cmd
> ;; Got answer:
> ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 38526
> ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
> 
> ;; OPT PSEUDOSECTION:
> ; EDNS: version: 0, flags:; udp: 512
> ;; QUESTION SECTION:
> ;195.5.90.45.in-addr.arpa.      IN      PTR
> 
> ;; ANSWER SECTION:
> 195.5.90.45.in-addr.arpa. 43200 IN      PTR     list.sys4.de.
> 
> ;; Query time: 54 msec
> ;; SERVER: 192.168.178.1#53(192.168.178.1)
> ;; WHEN: Wed Jun 17 11:44:26 CEST 2026
> ;; MSG SIZE  rcvd: 79
> 
> 
> The TTL of 43200 is high, so your platform should be able to keep this 
> cached
> for a long time.
> 
> It seems (speculation!) the problem is somewhere in your DNS stack, but 
> we
> don't know yet. As Wietse's put it many years ago on the Postfix-Users 
> list:
> "Measure! Don't speculate!".

This is true!

> As suggested by other start by looking at your log. If the message 
> persists
> claiming Postfix can't find the reverse PTR and I - the guy running the 
> DNS
> stack for list.sys4.de - have just proven it exists, then the question 
> is: Why
> wouldn't Postfix know then? Between the sys4 nameservers and your 
> Postfix
> there's your DNS stack. I would assume to find the error there.

I would agree. Reverse DNS exists, but I am still looking at why it is 
not seeing reverse DNS once in a while.

> - Are you running a chrooted Postfix and it can't query the right DNS
>   resolvers?

Not running a chrooted Postfix.

> - What do your DNS resolvers tell if you ask them on command line about
>   list.sys4.de PTRs?
> 
>     $ dig +short -x 2a03:4000:20:189::195
>     $ dig +short -x 45.90.5.195

#dig +short -x 2a03:4000:20:189::195

#dig +short -x 45.90.5.195
list.sys4.de.

The IPV6 returns nothing, so I would think that is the problem, but the 
error is with an IPv4 address.

I have not been able to get an IPv6 address from my ISP.

Kind Regards,
Al
_______________________________________________
Postfix-users mailing list -- [email protected]
To unsubscribe send an email to [email protected]