anchor.diff:      ''
       + optionalString (cfg.virtual != "") ''
         virtual_alias_maps = hash:/etc/postfix/virtual
  +    ''
  +    + optionalString (cfg.transport != "") ''
  +      transport_maps = hash:/etc/postfix/transport
       ''
       + cfg.extraConfig;
   
  
positive.code:         default = "";
          description = "
            Entries for the virtual alias map, cf. man-page virtual(8).
          ";
        };
  
  
negative.code:           ln -sf ${virtualFile} /var/postfix/conf/virtual
            ln -sf ${mainCfFile} /var/postfix/conf/main.cf
            ln -sf ${masterCfFile} /var/postfix/conf/master.cf
            ln -sf ${transportFile} /var/postfix/conf/transport
  
            ${pkgs.postfix}/sbin/postalias -c /var/postfix/conf /var/postfix/conf/aliases
            ${pkgs.postfix}/sbin/postmap -c /var/postfix/conf /var/postfix/conf/virtual
  