--- #YAML start Beispielsscript zur Installation und Konfiguration eines Mailservers
    name: install and configure MX
    hosts: mxtest.dmz.mailserver.guru
    become: yes

    vars: 
       mx_port_value : 25
   
    tasks:
    -name: Install Postfix
       yum: <code to install the MX>
    
    -name: Ensure the installed service is enabled and running
    service:
      name: <your service name>

… #YAML end syntax