"Topic not found" Message for non-logged in users
When users click on a link in an email forum subscription post without being logged into the Commons, they see the error message "Topic not found" if the forum is private and they haven't logged in. Some more user-friendly message, such as "Because this post was published in a private forum, you must log in to the Commons before reading it." or something to that effect.
I'm listing this as a feature, as it's not really a bug.