After installing postfix with autoyast on openSuSE 13.2,  I get 
myhostname = linux-in83.site
in my postfix main.cf

Below are the autoyast entries refering to mail and dns. I crossed out the
domains used, but setting the hostname in generla works. $(hostname) is used in
the init-script successfully.

Where does this weird (linux-in83.site) hostname name come from?

 <mail>
    <connection_type config:type="symbol">permanent</connection_type>
    <from_header>XXX</from_header>
    <listen_remote config:type="boolean">false</listen_remote>
    <masquerade_users config:type="list">
      <masquerade_user>
        <address>XXX</address>
        <user>root</user>
      </masquerade_user>
    </masquerade_users>
    <mta config:type="symbol">postfix</mta>
    <outgoing_mail_server>XXX</outgoing_mail_server>
    <postfix_mda config:type="symbol">local</postfix_mda>
    <use_amavis config:type="boolean">false</use_amavis>
  </mail>

  <networking>
    <keep_install_network config:type="boolean">true</keep_install_network>
    <dhcp_options>
      <dhclient_client_id/>
      <dhclient_hostname_option>AUTO</dhclient_hostname_option>
    </dhcp_options>
    <dns>
     <dhcp_hostname config:type="boolean">true</dhcp_hostname>
     <dhcp_resolv config:type="boolean">true</dhcp_resolv>
    </dns>