When users open the mail files of other users that they do not have access to see emails of, they have noticed that they can now see all of the person's folder names in the Notes account. In version 7, this was not the case.
If the environment have default access setup to allow access to see Public documents - users can see each others' Calendars by default (unless someone locks down the ACL).
Once you convert the mailfile to the 8.5.x template, the folder names become visible.

Starting in Lotus Notes 8.5.3, a new UI setting was introduced in Mail Preferences -> "Prohibit access to folders for users with Calendar, To Do's, and Contact access only".


Technote #1580005: Folder names are now public in the 8.5 template