However, mu4e’s user-interface is quite different. mu4e’s mail handling (deleting, moving, etc.) is inspired by Wanderlust6 (another Emacs-based e-mail client), mutt7 and the dired file-manager for emacs.
mu4e keeps all the ‘state’ in your maildirs, so you can easily switch between clients, synchronize over IMAP, backup with rsync and so on. The Xapian-database that mu maintains is merely a cache; if you delete it, you won’t lose any information.