Article Previews

As I understand it, by default MODx hides documents for which a person does not have permission. I’m wondering if it is possible to hide the article but still leave a snippet so when people click it they are presented with a message such as "Sorry, you do not have permission to access this article." Is that possible with the software?

No.. if user doesn’t have rights to some document, the framework doesn’t return that document in any queries to the database. You could do those snipplets in another documents.. or if you really want it, you could always make an function yourself that will get the "protected" documents too and a snippet to use that what lists the things you want..