After using your Plesk server for some time, you might want to, or have to change your server’s hostname. Assuming your server runs Fedora Core or RedHat, you’ll have to make changes in the following locations
Your current hostname should be here behind the server’s IP address, change this to the new hostname
You should have a HOSTNAME variable here, change this to your new hostname.
This contains the old hostname, change it to your new hostname to make qmail identify itself as the new hostname.
You should have a ServerName variable here, change it to your new hostname.
Change the servers hostname while it’s running, normally this is set at boot.
Set the new hostname inside Plesk’s database:
mysql -u admin -pcat /etc/psa/.psa.shadow use psa; update misc set val=’NEWHOSTNAME’ where param=’FullHostName’;
Now restart Plesk to activate your changes:
/etc/init.d/psa stopall /etc/init.d/psa stop /etc/init.d/psa start