Added mu4e configuration

I might do a full switch from Gnus to mu4e honestly

org/config/spacemacs.org

@@ -82,6 +82,7 @@
     - [[#general-options][General options]]
     - [[#visual-configuration-1][Visual configuration]]
   - [[#lsp][LSP]]
+  - [[#mu4e][Mu4e]]
   - [[#miscellaneous-1][Miscellaneous]]
     - [[#evil][Evil]]
     - [[#default-modes][Default modes]]
@@ -331,7 +332,18 @@
     As described below,  I use Gnus as  my main email client.  Therefore, I have
     the gnus layer enabled:
     #+BEGIN_SRC emacs-lisp
-    gnus
+      gnus
+    #+END_SRC
+
+    I am also currently testing ~mu4e~, so  let’s enable it and tell Emacs where
+    mu4e is  installed. I also tell  mu4e to use maildirs  extensions, use async
+    operations, where to keep attachments, and enable the mu4e modeline.
+    #+BEGIN_SRC emacs-lisp
+      (mu4e :variables
+            mu4e-installation-path "/usr/share/emacs/site-lisp"
+            mu4e-use-maildirs-extension t
+            mu4e-enable-mode-line t
+            mu4e-attachment-dir "~/Documents")
     #+END_SRC
 
 *** Emacs
@@ -1854,11 +1866,14 @@
         "ogD" 'turn-on-gnus-dired-mode
         "ogd" 'gnus-summary-delete-article
         "ogf" 'gnus-summary-mail-forward
+        "ogm" 'gnus-group-mail
         "ogo" 'my-gnus-group-list-subscribed-groups
         "ogr" 'gnus-summary-insert-new-articles
         "ogs" 'message-send-and-exit)
     #+END_SRC
 
+    #+RESULTS:
+
 *** Hooks
     :PROPERTIES:
     :CUSTOM_ID: h-5208e53f-d2e7-4dc1-a081-964ac1c90d4b
@@ -1980,6 +1995,55 @@
      (tooltip-mode 1)
    #+END_SRC
 
+** Mu4e
+   :PROPERTIES:
+   :CUSTOM_ID: h-ba4a69ff-38a6-498a-b076-a514bbf0701f
+   :END:
+
+   #+BEGIN_SRC emacs-lisp
+     (setq mu4e-maildir "~/.mail"
+           mu4e-trash-folder "/Trash"
+           mu4e-refile-folder "/Archive"
+           mu4e-sent-folder "/Sent"
+           mu4e-get-mail-command "mbsync -a"
+           mu4e-update-interval 60
+           mu4e-compose-signature-auto-include t
+           mu4e-view-show-images t
+           mu4e-view-show-addresses t)
+   #+END_SRC
+
+   Bookmarks
+   #+BEGIN_SRC emacs-lisp
+     (setq mu4e-bookmarks
+           `(("flag:unread AND NOT flag:trashed" "Unread messages" ?u)
+             ("date:today..now" "Today's messages" ?t)
+             ("date:7d..now" "Last 7 days" ?w)
+             ("mime:image/*" "Messages with images" ?p)
+             (,(mapconcat 'identity
+                          (mapcar
+                           (lambda (maildir)
+                             (concat "maildir:" (car maildir)))
+                           mu4e-maildir-shortcuts) " OR ")
+              "All inboxes" ?i)))
+   #+END_SRC
+
+   Enable OS notifications.
+   #+BEGIN_SRC emacs-lisp
+     (setq mu4e-enable-notifications t)
+     (with-eval-after-load 'mu4e-alert
+       (mu4e-alert-set-default-style 'notifications))
+   #+END_SRC
+
+   #+BEGIN_SRC emacs-lisp
+     (add-hook 'mu4e-view-mode-hook 'visual-fill-column-mode)
+   #+END_SRC
+
+   Vertical split
+   #+BEGIN_SRC emacs-lisp
+     (setq mu4e-split-view 'vertical
+           mu4e-headers-visible-columns 80)
+   #+END_SRC
+
 ** Miscellaneous
    :PROPERTIES:
    :CUSTOM_ID: h-cee08965-745a-4a6f-b04e-bf1638342698