If you would like the existence of your mailing list to be hidden, you can choose to hide your mailing list. A hidden mailing list does not appear in the web interface menus, and does not appear in the "lists" email command.
The web interface pages for a hidden mailing list are still available, if you use the direct URLs to go to them. For example, the join= and enter= pages are still there, but the user needs to be pointed directly to them.