Hello,
How to correctly replace “localhost.localdomain” after installation.
So far I ran the following commands to replace the localhost.localdomain with mail.mydomain.com
cat /etc/hostname
hostnamectl set-hostname mail.mydomain.com
hostnamectl
All looks fine, however there is a problem because mail-tester.com is now telling me,
Your IP address xx.xxx.xxx.xx is associated with the domain mail.mydomain.com.
Nevertheless your message appears to be sent from localhost.localdomain.
You may want to change your pointer (PTR type) DNS record and the host name of your server to the same value.
Here are the tested values for this check:
IP: xx.xxx.xxx.xx
HELO: localhost.localdomain
rDNS: mail.mydomain.com
I replaced the above IP and domain for privacy.
I also found this file.
/etc/hosts
Contents are,
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6
Maybe I should replace localhost.localdomain in here too ? It looks as if I just need to get the HELO: Updated ?
I don’t want to guess or take any chances, I’ve already made a mess of this server twice this week, third time lucky I hope!
Any help would be very much appreciated 
