If you had PCs with Microsoft Windows Messaging, and included Lotus Notes as a Service, so that Lotus Notes Inbox is added to the Outlook folder. This process adds 5 hidden folders.
-- (~MAPISP(Internal))
-- (Search Root)
-- (IPMVIEWS)
-- (IPMCOMMONVIEWS)
-- (Rules)
All marked in design properties to not allow design refresh / replace or modify.
When you upgrade the Mail file, because (Rules) is all ready there with design properties set to not allow refresh this Folder is not updated, therefore RULES is not visible but in the design it appears.
Deselect "Do not allow design refresh / replace or modify" and refresh the design with R5 Mail Template, the correct Rules folder will be available.