You should be able to. Try a simpler syntax first, e.g.
Notes://server/mail/mailfilename.nsf/. You should be able to just paste the notes:// protocol address into the browser address window, hit enter, and it would launch the mail file in Notes.
Another way to ensure you have the proper syntax is to bring up a document’s properties, then highlight and copy the notes:// protocol address displayed on the + tab.
Pasting that address into the browser window and hitting enter should bring up the notes document. Remove the last unid and the view will open. REmove the view UNID and the database will open to its default view.
If that doesn’t work, there is still something wrong with your registry.