I have a doub about configuring suse for zimbra

in dns the mx record for the server is mail.sienic.site with A record mail, but in the hosts file suse setup the real hostname of the server in the hosts file as follow: localhost server03.sienic.site server03

(server03 is the real name of the server in /etc/hostname)

instead of localhost mail.sienic.site mail

in this scenario what would be the correct form of the hosts file?

the other thing is tha zimbra requires the first line to be localhost.localdomain localhost

but suse default is localhost

is ok to change to meet zimbra requirements or it will break things?