I am investigating the feasibility of exposing content libraries to our customer portal users and am wondering if content subscriptions functionality can be turned off for portal users? you have the ability to turn off email notifications on a per-user basis, but this really does no good if you still have the subscription buttons available. It would be very confusing for our customers if they subscribed to content expecting to receive email alerts, and never received them.
The answer I've received from our CSM is that there is no standard way of doing this. You would need to build a custom Content solution using Visualforce. This is very unfortunate.
