anchor.diff:        description = ''
           Location that dovecot will use for mail folders. Dovecot mail_location option.
         '';
  +    };
  +
  +    mailUser = mkOption {
  +      type = types.nullOr types.str;
  +      default = null;
  +      description = "Default user to store mail for virtual users.";
  +    };
  +
  +    mailGroup = mkOption {
  +      type = types.nullOr types.str;
  +      default = null;
  +      description = "Default group to store mail for virtual users.";
       };
   
       modules = mkOption {
  
positive.code:           fi
             ${pkgs.dovecot_pigeonhole}/bin/sievec '${stateDir}/sieve/${to}'
          '') cfg.sieveScripts)}
          chown -R '${cfg.user}:${cfg.group}' ${stateDir}/sieve
        '';
      };
  
  
negative.code: 
      ''
        default_internal_user = ${cfg.user}
        ${optionalString (cfg.mailUser != null) "mail_uid = ${cfg.mailUser}"}
        ${optionalString (cfg.mailGroup != null) "mail_gid = ${cfg.mailGroup}"}
  
        mail_location = ${cfg.mailLocation}
  
  