[SOLVED] Double hostname in HELO server1.server1.example.com

Mar 26, 2023
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Hi there,

Our user is complaining about emails not being received when smart-hosted out via our PMG cluster. They did a mail-tester.com check and have provided this:

Code:
IP: 1.2.3.4
HELO: server1.server1.example.com
rDNS: server1.example.com
FAIL

We've checked;

/etc/hostname - the short hostname (pmgchanged, the part before the first .,) needs to be entered there.

Code:
root@server1:~# cat /etc/hostname
server1

/etc/hosts - there needs to be an entry with the main IP pointing to the short hostname and FQDN:

Code:
root@server1:~# cat /etc/hosts
127.0.0.1 localhost.localdomain localhost
1.2.3.4 server1.example.com server1

/etc/resolv.conf - needs to contain the domain name part as search - This can also be accomplished in the GUI (on the main Configuration Menu entry):

Code:
root@server1:~# cat /etc/resolv.conf
search server1.example.com
nameserver 127.0.0.1

Checking the mail.log we can see things like:

Code:
root@server1:~# tail -5000 /var/log/mail.log | grep server1.server1
Nov  2 17:29:06 server1 postfix/smtp[3229918]: 93A4A1C1085: to=<x.x@x.com>, relay=mail-01.x.com[9.8.7.6]:25, delay=244119, delays=244119/0/0.73/0.12, dsn=4.7.1, status=deferred (host mail-01.x.com[9.8.7.6] said: 450 4.7.1 <server1.server1.example.com>: Helo command rejected: Host not found (in reply to RCPT TO command))

Could you please offer any help here?

Thanks.
C
 
Last edited:

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