There is no limit, but obviously the cost will be very high if you have thousands of lists. They must all be polled every N minutes, and when a local user sends a LIST command he will get a listing of thousands of lists (when he probably meant to see the network-wide ones only), and you can be sure this listing will take time to prepare and send back. There are many other instances where a lot of CPU time will be burnt, for instance every night the server will want to send updates for any non local list which has changed since last time. Well you may only have 5 non-local lists, but it will still have to scan the N thousands before it knows that. Eric