Update mu4e README, add mbsync config section

modules/email/mu4e/README.org

@@ -12,11 +12,12 @@
   - [[#arch-linux][Arch Linux]]
   - [[#nixos][NixOS]]
   - [[#opensuse][openSUSE]]
-  - [[Debian/Ubuntu]]
+  - [[#debianubuntu][Debian/Ubuntu]]
 - [[#features][Features]]
 - [[#configuration][Configuration]]
   - [[#offlineimap][offlineimap]]
   - [[#mbsync][mbsync]]
+  - [[#mu-and-mu4e][mu and mu4e]]
 - [[#troubleshooting][Troubleshooting]]
   - [[#no-such-file-or-directory-mu4e][=No such file or directory, mu4e=]]
   - [[#void-function-org-time-add-error-on-gentoo][~(void-function org-time-add)~ error on Gentoo]]
@@ -105,20 +106,53 @@ sudo apt-get install maildir-utils # mu
 
 * Configuration
 ** offlineimap
-This module uses =mbsync= by default. To change this, change ~+mu4e-backend~:
+This module uses =mbsync= by default. To use =offlineimap=, change ~+mu4e-backend~:
 
 #+BEGIN_SRC emacs-lisp
 (setq +mu4e-backend 'offlineimap)
 #+END_SRC
 
-Then you must set up offlineimap and index your mail:
+Next, you need to write a configuration file for =offlineimap=. Mine can be found
+[[https://github.com/hlissner/dotfiles/tree/master/shell/mu][in my dotfiles repository]]. It is configured to download mail to ~\~/.mail~. I
+use [[https://www.passwordstore.org/][unix pass]] to securely store my login credentials. You can find a *very*
+detailed configuration [[https://github.com/OfflineIMAP/offlineimap/blob/master/offlineimap.conf][here]].
 
-1. Write a ~\~/.offlineimaprc~. Mine can be found [[https://github.com/hlissner/dotfiles/tree/master/shell/mu][in my dotfiles repository]]. It
-   is configured to download mail to ~\~/.mail~. I use [[https://www.passwordstore.org/][unix pass]] to securely
-   store my login credentials. You can find a *very* detailed configuration
-   [[https://github.com/OfflineIMAP/offlineimap/blob/master/offlineimap.conf][here]].
-2. Download your email: ~offlineimap -o~ (may take a while)
-3. Index it with mu: ~mu index --maildir ~/.mail~
+Next you can download your email with ~offlineimap -o~. This may take a while,
+especially if you have thousands of mails.
+
+You can now proceed with the [[*mu and mu4e][mu and mu4e]] section.
+
+** mbsync
+The steps needed to set up =mu4e= with =mbsync= are very similar to the ones for
+[[*offlineimap][offlineimap]].
+
+Start with writing a ~\~/.mbsyncrc~. An example for GMAIL can be found on
+[[http://pragmaticemacs.com/emacs/migrating-from-offlineimap-to-mbsync-for-mu4e/][pragmaticemacs.com]]. A non-GMAIL example is available as a gist [[https://gist.github.com/agraul/60977cc497c3aec44e10591f94f49ef0][here]]. The [[http://isync.sourceforge.net/mbsync.html][manual
+page]] contains all needed information to set up your own.
+
+Next you can download your email with ~mbsync --all~. This may take a while, but
+should be quicker than =offlineimap= ;).
+
+You can now proceed with the [[*mu and mu4e][mu and mu4e]] section.
+
+** mu and mu4e
+You should have your email downloaded already. If you have not, you need to set
+=offlineimap= or =mbsync= up before you proceed.
+
+Before you can use =mu4e= or the cli program =mu=, you need to index your email
+initially. How to do that differs a little depending on the version of =mu= you
+use. You can check your version with ~mu --version~.
+
+For =mu= *>=1.4* you need to run two commands:
+#+BEGIN_SRC sh
+mu init --maildir ~/.mail --my-address email@example.com
+mu index
+#+END_SRC
+
+=mu= *<1.4* only requires one command:
+#+BEGIN_SRC sh
+mu index --maildir ~/.mail
+#+END_SRC
 
 Then configure Emacs to use your email address:
 
@@ -130,12 +164,11 @@ Then configure Emacs to use your email address:
     (mu4e-trash-folder      . "/Lissner.net/Trash")
     (mu4e-refile-folder     . "/Lissner.net/All Mail")
     (smtpmail-smtp-user     . "henrik@lissner.net")
-    (user-mail-address      . "henrik@lissner.net")
+    (user-mail-address      . "henrik@lissner.net")    ;; only needed for mu < 1.4
     (mu4e-compose-signature . "---\nHenrik Lissner"))
   t)
 #+END_SRC
 
-** TODO mbsync
 * Troubleshooting
 ** =No such file or directory, mu4e=
 You will get =No such file or directory, mu4e= errors if you don't run ~doom