Hello,
I have been a Proxmox Mail Gateway user for many years, but only became a forum member today. Unfortunately, only today (far too late, admittedly) I noticed that there were DNSSEC issues with one of my DNS zones. The zone itself hasn’t changed for quite some time, and the pre-signed zone that was transferred to the slaves has expired. So far, so “good”.
However, I then noticed that during this period my Proxmox MG setup refused to validate recipient addresses.
The problem with my zone was quickly identified by https://dnssec-debugger.verisignlabs.com/, namely:
(The cause was that after migrating the DNS master, I forgot to reinstall/activate/whatever a cron job that re-signs zones which do not change very often.)
Now to my actual question:
Why the "Recipient address rejected: Domain not found;"? Or to be more precice: "Why the "Domain not found"?
The mail server behind @example.org is located in a private network behind this PMG host and is configured in the transport configuration using its IP address, without “use MX”.So what causes the PMG host to perform any kind of DNS lookup here?
After updating the zone, everything started working again immediately.
Yes, my local resolver validates DNSSEC, and no, I didn’t notice this for five days (it’s a pure mail domain, and a few emails did get through).
Do you have any ideas on how to better understand this message, or whether I might have some kind of configuration mistake somewhere?
I have been a Proxmox Mail Gateway user for many years, but only became a forum member today. Unfortunately, only today (far too late, admittedly) I noticed that there were DNSSEC issues with one of my DNS zones. The zone itself hasn’t changed for quite some time, and the pre-signed zone that was transferred to the slaves has expired. So far, so “good”.
However, I then noticed that during this period my Proxmox MG setup refused to validate recipient addresses.
Code:
2026-04-10T16:52:04.585680+02:00 transport postfix/smtpd[617331]: connect from p-west3-cluster1-host2-snip4-4.eps.apple.com[57.103.73.145]
2026-04-10T16:52:05.248117+02:00 transport postfix/smtpd[617331]: Anonymous TLS connection established from p-west3-cluster1-host2-snip4-4.eps.apple.com[57.103.73.145]: TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519 server-signature RSA-PSS (2048 bits) server-digest SHA256
2026-04-10T16:52:05.632378+02:00 transport postfix/smtpd[617331]: NOQUEUE: reject: RCPT from p-west3-cluster1-host2-snip4-4.eps.apple.com[57.103.73.145]: 450 4.1.2 <user@example.org>: Recipient address rejected: Domain not found; from=<privaterelay.bounce.zxt6rh22n8@privaterelay.appleid.com> to=<user@example.org> proto=ESMTP helo=<outbound.ms.icloud.com>
2026-04-10T16:52:05.798969+02:00 transport postfix/smtpd[617331]: disconnect from p-west3-cluster1-host2-snip4-4.eps.apple.com[57.103.73.145] ehlo=2 starttls=1 mail=1 rcpt=0/1 data=0/1 rset=1 quit=1 commands=6/8The problem with my zone was quickly identified by https://dnssec-debugger.verisignlabs.com/, namely:
Code:
RRSIG=14006 is expiredNow to my actual question:
Why the "Recipient address rejected: Domain not found;"? Or to be more precice: "Why the "Domain not found"?
The mail server behind @example.org is located in a private network behind this PMG host and is configured in the transport configuration using its IP address, without “use MX”.So what causes the PMG host to perform any kind of DNS lookup here?
After updating the zone, everything started working again immediately.
Yes, my local resolver validates DNSSEC, and no, I didn’t notice this for five days (it’s a pure mail domain, and a few emails did get through).
Do you have any ideas on how to better understand this message, or whether I might have some kind of configuration mistake somewhere?
.