anchor.diff:    ;
   
     aliasesFile = pkgs.writeText "postfix-aliases" aliases;
  +  canonicalFile = pkgs.writeText "postfix-canonical" cfg.canonical;
     virtualFile = pkgs.writeText "postfix-virtual" cfg.virtual;
     localRecipientMapFile = pkgs.writeText "postfix-local-recipient-map" (concatMapStrings (x: x + " ACCEPT\n") cfg.localRecipients);
     checkClientAccessFile = pkgs.writeText "postfix-check-client-access" cfg.dnsBlacklistOverrides;
  
positive.code:     (mkIf haveAliases {
        services.postfix.aliasFiles.aliases = aliasesFile;
      })
      (mkIf haveTransport {
        services.postfix.mapFiles.transport = transportFile;
      })
  
negative.code:         description = "
            Delimiter for address extension: so mail to user+test can be handled by ~user/.forward+test
          ";
        };
  
        canonical = mkOption {
          type = types.lines;
          default = "";
          description = ''
            Entries for the <citerefentry><refentrytitle>canonical</refentrytitle>
            <manvolnum>5</manvolnum></citerefentry> table.
          '';
        };
  
        virtual = mkOption {
  