anchor.diff:      + optionalString (cfg.recipientDelimiter != "") ''
         recipient_delimiter = ${cfg.recipientDelimiter}
       ''
  -    + optionalString (cfg.virtual != "") ''
  +    + optionalString haveAliases ''
  +      alias_maps = hash:/etc/postfix/aliases
  +    ''
  +    + optionalString haveTransport ''
  +      transport_maps = hash:/etc/postfix/transport
  +    ''
  +    + optionalString haveVirtual ''
         virtual_alias_maps = hash:/etc/postfix/virtual
  -    ''
  -    + optionalString (cfg.transport != "") ''
  -      transport_maps = hash:/etc/postfix/transport
  -    + optionalString (cfg.postmasterAlias != "" || cfg.rootAlias != "" || cfg.extraAliases != "") ''
  -      alias_maps = hash:/var/postfix/conf/aliases
       ''
       + cfg.extraConfig;
   
  
positive.code:   group = cfg.group;
    setgidGroup = cfg.setgidGroup;
  
    mainCf =
      ''
        compatibility_level = 2
  
        queue_directory = /var/postfix/queue
        command_directory = ${pkgs.postfix}/sbin
        daemon_directory = ${pkgs.postfix}/libexec/postfix
  
        mail_owner = ${user}
        default_privs = nobody
  
negative.code: 
      environment = {
        etc = singleton
          { source = "/var/lib/postfix/conf";
            target = "postfix";
          };
  
  