Special case: IMAP Shared Folders:

If you are accessing an IMAP server, there may be shared folders. Exhaustive experimentation reveals that you can access a shared IMAP folder called Users/Shared/FunStuff by entering c imap://mail.server.com/Users.Shared.FunStuff. That's a lot of typing, so save yourself some trouble and bind that expression to a keystroke (see section 4.3).