You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Greetings,
"hostname does not resolve to address" but, in fact the IP address resolves to the correct name. I get this kind of rejection for some hosts from time to ttime
2024-01-19T11:25:22.303105+00:00 proxmox postfix/smtpd[190151]: warning: hostname domain.com does not resolve to address xx.xx.xx.xx
2024-01-19T11:25:22.303302+00:00 proxmox postfix/smtpd[190151]: connect from unknown[xx.xx.xx.xx]
2024-01-19T11:25:22.318490+00:00 proxmox postfix/smtpd[190151]: NOQUEUE: reject: RCPT from unknown[xx.xx.xx.xx]: 450 4.7.25 Client host rejected: cannot find your hostname, [185.58.81.13]; from=<no.reply.domain.com> to=<domain2.com> proto=ESMTP helo=<domain.com>
2024-01-19T11:25:22.324004+00:00 proxmox postfix/smtpd[190151]: disconnect from unknown[xx.xx.xx.xx] ehlo=1 mail=1 rcpt=0/1 quit=1 commands=3/4
What can I do to solve this?
thank you
But the error message says that it could not be resolved. That's just a fact. The cause can be incorrect DNS settings, a TTL that is too short and possibly caused caching problems, or a temporary inaccessibility of the DNS resolver (unless the local one is used).
Whatever the cause, the error message remains correct and reflects the actual situation at that moment.
Just found out that IP address is resolved but ICMP looks to be blocked (mail.edp.pt), could it be the cause?
no - postfix does not rely on icmp to detect reachability ...
as
@sb-jw
correctly pointed out - the issue is with DNS as seen on the PMG.
you can test this by installing drill (`apt install ldnsutils`) and checking on the PMG:
* `drill mail.edp.pt` (use the hostname you see in the logs here!
* `drill -x <ip.ad.dr.es>` (use the ip-address from the logs here
those should coincide.
no - postfix does not rely on icmp to detect reachability ...
as
@sb-jw
correctly pointed out - the issue is with DNS as seen on the PMG.
you can test this by installing drill (`apt install ldnsutils`) and checking on the PMG:
* `drill mail.edp.pt` (use the hostname you see in the logs here!
* `drill -x <ip.ad.dr.es>` (use the ip-address from the logs here
those should coincide.
Thank you for your reply, both, direct and reverse ping get correct answers
root@proxmox:~# drill mail.edp.pt
;; ->>HEADER<<- opcode: QUERY, rcode: NOERROR, id: 35949
;; flags: qr rd ra ; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;; mail.edp.pt. IN A
;; ANSWER SECTION:
mail.edp.pt. 30 IN A 185.58.81.13
;; AUTHORITY SECTION:
;; ADDITIONAL SECTION:
;; Query time: 13 msec
;; SERVER: 195.23.129.126
;; WHEN: Mon Jan 22 09:41:05 2024
;; MSG SIZE rcvd: 45
root@proxmox:~# drill -x 185.58.81.13
;; ->>HEADER<<- opcode: QUERY, rcode: NOERROR, id: 5166
;; flags: qr rd ra ; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;; 13.81.58.185.in-addr.arpa. IN PTR
;; ANSWER SECTION:
13.81.58.185.in-addr.arpa. 38400 IN PTR mail.edp.pt.
;; AUTHORITY SECTION:
;; ADDITIONAL SECTION:
;; Query time: 13 msec
;; SERVER: 195.23.129.126
;; WHEN: Mon Jan 22 09:41:39 2024
;; MSG SIZE rcvd: 68
I believe I'm experiencing the same issue, PMG 8.1.2
I have both Mail Proxy > Options > Reject unknown clients & Reject unknown senders enabled.
Emails are being rejected like this:
rejected >> hostname mail-vs1-f44.google.com does not resolve to address 209.85.217.44
I should add that, so far, each time I've had to deal with this issue, it was related to a google.com domain:
2024-06-03T11:43:46.671317-04:00 proxmox postfix/smtpd[958415]: warning:
hostname mail-qk1-f173.google.com
does not resolve to address 209.85.222.173
2024-06-03T11:43:46.671463-04:00 proxmox postfix/smtpd[958415]: connect from unknown[209.85.222.173]
2024-06-03T11:43:46.836121-04:00 proxmox postfix/smtpd[958415]: NOQUEUE: reject: RCPT from unknown[209.85.222.173]: 450 4.7.25 Client host rejected: cannot find your hostname
I solve it by whitelisting the sender domain, which in this case was a @umich.edu addy.
My guess is that the sender has their domain name hosted with Google and use GMAIL as their MX. So, maybe, PMG see's google.com but the sender is something diff?
The Proxmox community has been around for many years and offers help and support for
Proxmox VE, Proxmox Backup Server, and Proxmox Mail Gateway.
We think our community is one of the best thanks to people like you!
The Proxmox team works very hard to make sure you are running the best software and getting stable updates and security enhancements, as well as quick enterprise support. Tens of thousands of happy customers have a Proxmox subscription. Get yours easily in our online shop.
Buy now!
We value your privacy
We use essential
cookies
to make this site work, and optional cookies to enhance your experience.
