anchor.diff:          description = "The collection of hosted maillists";
         };
   
  +      maintInterval = mkOption {
  +        type = types.str;
  +        default = "20min";
  +        description = ''
  +          Time interval between mlmmj-maintd runs, see
  +          <citerefentry><refentrytitle>systemd.time</refentrytitle>
  +          <manvolnum>7</manvolnum></citerefentry> for format information.
  +        '';
  +      };
  +
       };
   
     };
  
positive.code:     system.activationScripts.mlmmj = ''
            ${pkgs.coreutils}/bin/mkdir -p ${stateDir} ${spoolDir}/${cfg.listDomain}
            ${pkgs.coreutils}/bin/chown -R ${cfg.user}:${cfg.group} ${spoolDir}
            ${lib.concatMapStrings (createList cfg.listDomain) cfg.mailLists}
            echo ${lib.concatMapStrings (virtual cfg.listDomain) cfg.mailLists} > ${stateDir}/virtuals
            echo ${lib.concatMapStrings (transport cfg.listDomain) cfg.mailLists} > ${stateDir}/transports
            ${pkgs.postfix}/bin/postmap ${stateDir}/virtuals
            ${pkgs.postfix}/bin/postmap ${stateDir}/transports
        '';
  
      systemd.services."mlmmj-maintd" = {
        description = "mlmmj maintenance daemon";
        wantedBy = [ "multi-user.target" ];
  
        serviceConfig = {
          User = cfg.user;
          Group = cfg.group;
  
negative.code: with lib;
  
  let
  
    concatMapLines = f: l: lib.concatStringsSep "\n" (map f l);
  
    cfg = config.services.mlmmj;
    stateDir = "/var/lib/mlmmj";
  