How do I change the Host Name?

[mrmarkuz (Markus Neuberger)]

Maybe you need to change the smtp banner?

Customizable Postfix SMTP banner host

The default SMTPD banner in Postfix is $hostname ESMTP $mail_name, which normally translates to something like <your_host_name> ESMTP Postfix. If the internal server name does not match the public DNS, the SMTP shows a hostname which may be incorrect, and make some email services reject messages or mark them as SPAM. It would be useful to have a way to override the default Postfix smtpd_banner configuration option. This can be done as easy as including a new template snippet named /etc/e-smit…