On a publication-by-publication basis, you can control the access that subscription servers have to a publication by marking the publication as either unrestricted or restricted.
A publication marked as unrestricted is visible to and can be subscribed to by any subscription server known to the publication server.
A publication marked as restricted is visible to only those subscription servers authorized for access. Servers not authorized for access cannot subscribe to the publication; they cannot even see it. As a result, users setting up subscriptions at servers not authorized for access will not even know of a restricted publication. At those servers, it will not appear in any list.