how to change server name

[lexcomputer]

Could anyone tell me how to change my server name

I got the result after run telnet mail.mydomain.com 25

220 server1.mydomain.com ESMTP Postfix

Then I would like to change from server1.mydomain.com to ns.yourdomain.net. How can I make change?

Thank you.

[falko]

Run
echo ns.yourdomain.net > /etc/hostname
/bin/hostname -F /etc/hostname

Also change your hostname in /etc/postfix/main.cf (myhostname and mydomain). Don't forget to restart Postfix.