Console login prompt doesn't display the system hostname and bash prompt displays system hostname after the # or ~ sign

Issue

• When connecting to the system console, the login prompt doesn't display the system hostname, as shown below

  Red Hat Enterprise Linux
  Kernel xxx on an yyy
  
   login: 
  

• After logging into the system using the console or SSH, the user prompt displays the system hostname (vm-rhel7 in the example) after the pound (#) or dollar ($) sign, as shown below

  $ ssh root@vm-rhel7
  Last login: Thu Jan 31 09:09:25 2019
   ~]# @vm-rhel7
  

• The postfix service fails to start and displays the following messages in the journal (vm-rhel7 is the system hostname in the example)

  [...] postfix[3451]: warning: valid_hostname: invalid character 13(decimal): vm-rhel7?
  [...] postfix[3451]: fatal: unable to use my own hostname
  [...] systemd[1]: postfix.service: control process exited, code=exited status=1
  [...] systemd[1]: Failed to start Postfix Mail Transport Agent.
  [...] systemd[1]: Unit postfix.service entered failed state.
  [...] systemd[1]: postfix.service failed.
  

• The NetworkManager service displays the following message in the journal (vm-rhel7 is the system hostname in the example)

  NetworkManager[3045]: <info>  [XXX] policy: set-hostname: current hostname was changed outside NetworkManager: 'vm-rhel7'