said: 450 4.7.1 <spa02.xxx.com>: Helo command rejected: Host not found (in reply to RCPT TO command))

[phalla]

Dear support,

Please help to resolve my problem.
I cannot send an email out. I got a message bound to like this:

Dec 28 20:53:45 spa02 postfix/smtp[6517]: 0A03C14208B: to=<incident@xxx.h>, relay=mail.xxxx.h[103.112.17.51]:25, delay=1.1, delays=0.1/0/0.61/0.37, dsn=4.7.1, status=deferred (host mail.xxxx.h[103.112.17.51] said: 450 4.7.1 <spa02.xxx.com>: Helo command rejected: Host not found (in reply to RCPT TO command))

Can you give me advice?

Warm Regards,
Phalla

 

[Stoiko Ivanov]

Seems the helo_name of your PMG does not resolve to a (public) IP address
The message is a reply from 103.112.17.51 - which seems to be configured so that it rejects mail from hosts which use a helo_name, which does not resolve to an IP address.

* what does the output of `hostname -f` from your PMG resolve to?
* have you modified the helo_name of your PMG installation?

I hope this helps

 

[phalla]

Seems the helo_name of your PMG does not resolve to a (public) IP address
The message is a reply from 103.112.17.51 - which seems to be configured so that it rejects mail from hosts which use a helo_name, which does not resolve to an IP address.

* what does the output of `hostname -f` from your PMG resolve to?
* have you modified the helo_name of your PMG installation?

I hope this helps

My hostname: spa02.mydomain.com

I don't understand this point * have you modified the helo_name of your PMG installation?
Do you mean that this option on PMG?

 

[Stoiko Ivanov]

My hostname: spa02.mydomain.com

what's the output of `dig spa02.mydomain.com @8.8.8.8` ?

I don't understand this point * have you modified the helo_name of your PMG installation?
Do you mean that this option on PMG?

no - if you have not modified the postfix configuration templates then this point does not apply

 

[phalla]

what's the output of `dig spa02.mydomain.com @8.8.8.8` ?


no - if you have not modified the postfix configuration templates then this point does not apply

Please check it.
spa02:~# dig spa02.mydomain.com @8.8.8.8

; <<>> DiG 9.11.5-P4-5.1-Debian <<>>spa02.mydomain.com @8.8.8.8
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 20861
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;spa02.mydomain.com. IN A

;; AUTHORITY SECTION:
mydomain.com. 1799 IN SOA ns1.mydomain.com. system.mydomain.com. 2020121002 3600 1800 1209600 86400

;; Query time: 42 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Tue Dec 29 17:21:56 +07 2020
;; MSG SIZE rcvd: 99

 

[Stoiko Ivanov]

spa02:~# dig spa02.mydomain.com @8.8.8.8

ok this says that spa02.mydomain.com does not resolve to an IP -> which is what causes the remote mailserver to reject your mail.

Just to be clear - spa02.mydomain.com is actually the hostname of your PMG or did you change mydomain.com for anonymization purposes?!

in any case add a DNS entry for spa02.mydomain.com to the mydomain.com zone pointing to the public IP address of PMG