anchor.diff:    ;
   
     aliasesFile = pkgs.writeText "postfix-aliases" aliases;
  +  virtualFile = pkgs.writeText "postfix-virtual" cfg.virtual;
     mainCfFile = pkgs.writeText "postfix-main.cf" mainCf;
   
   in
  
positive.code:         example = "+";
          description = "
            Delimiter for address extension: so mail to user+test can be handled by ~user/.forward+test
          ";
        };
  
  
negative.code: 
        recipientDelimiter = ${cfg.recipientDelimiter}
      ''
      + optionalString (cfg.virtual != "") ''
        virtual_alias_maps = hash:/etc/postfix/virtual
      ''
      + cfg.extraConfig;
  
    aliases =
  