From: Kiso Katsuyuki <katsuyuki2388@gmail.com>

When kill and exit from a notmuch mode buffer
(notmuch-show-mode, notmuch-tree-mode,
notmuch-search-mode, notmuch-hello-mode, notmuch-message-mode),
return to the previous notmuch mode buffer. It's because
the previous notmuch buffer is often buried and I have to
select it with a buffer-switching command.
---
 emacs/notmuch-draft.el |  6 ++++--
 emacs/notmuch-lib.el   | 17 +++++++++++++++--
 emacs/notmuch-mua.el   |  7 +++++--
 emacs/notmuch-tree.el  |  6 ++++--
 4 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/emacs/notmuch-draft.el b/emacs/notmuch-draft.el
index fb7f4f55..8717f317 100644
--- a/emacs/notmuch-draft.el
+++ b/emacs/notmuch-draft.el
@@ -214,10 +214,12 @@ applied to newly inserted messages)."
     (set-buffer-modified-p nil)))
 
 (defun notmuch-draft-postpone ()
-  "Save the draft message in the notmuch database and exit buffer."
+  "Save the draft message in the notmuch database, exit buffer,
+and select the previous notmuch buffer."
   (interactive)
   (notmuch-draft-save)
-  (kill-buffer))
+  (kill-buffer)
+  (notmuch-select-previous-notmuch-buffer))
 
 (defun notmuch-draft-resume (id)
   "Resume editing of message with id ID."
diff --git a/emacs/notmuch-lib.el b/emacs/notmuch-lib.el
index 337b20ac..0371c23f 100644
--- a/emacs/notmuch-lib.el
+++ b/emacs/notmuch-lib.el
@@ -260,15 +260,28 @@ depending on the value of `notmuch-poll-script'."
 	  (error "Notmuch: poll script `%s' failed!" notmuch-poll-script)))
     (notmuch-call-notmuch-process "new")))
 
+(defun notmuch-select-previous-notmuch-buffer ()
+  "Select the previous notmuch buffer."
+  (catch 'get-notmuch-buffer
+    (dolist (buffer (buffer-list))
+      (let ((buffer-mode (buffer-local-value 'major-mode buffer)))
+	(when (memq buffer-mode '(notmuch-show-mode
+				  notmuch-tree-mode
+				  notmuch-search-mode
+				  notmuch-hello-mode
+				  notmuch-message-mode))
+	  (throw 'get-notmuch-buffer (switch-to-buffer buffer)))))))
+
 (defun notmuch-bury-or-kill-this-buffer ()
   "Undisplay the current buffer.
 
 Bury the current buffer, unless there is only one window showing
-it, in which case it is killed."
+it, in which case it is killed. Then, select the previous notmuch buffer."
   (interactive)
   (if (> (length (get-buffer-window-list nil nil t)) 1)
       (bury-buffer)
-    (kill-buffer)))
+    (kill-buffer))
+  (notmuch-select-previous-notmuch-buffer))
 
 (defun notmuch-documentation-first-line (symbol)
   "Return the first line of the documentation string for SYMBOL."
diff --git a/emacs/notmuch-mua.el b/emacs/notmuch-mua.el
index 93747b1c..c1d533f7 100644
--- a/emacs/notmuch-mua.el
+++ b/emacs/notmuch-mua.el
@@ -292,6 +292,7 @@ mutiple parts get a header."
 
 (define-key notmuch-message-mode-map (kbd "C-c C-c") #'notmuch-mua-send-and-exit)
 (define-key notmuch-message-mode-map (kbd "C-c C-s") #'notmuch-mua-send)
+(define-key notmuch-message-mode-map (kbd "C-c C-k") #'notmuch-mua-kill-buffer)
 (define-key notmuch-message-mode-map (kbd "C-c C-p") #'notmuch-draft-postpone)
 (define-key notmuch-message-mode-map (kbd "C-x C-s") #'notmuch-draft-save)
 
@@ -552,7 +553,8 @@ unencrypted.  Really send? "))))
 
 (defun notmuch-mua-send-and-exit (&optional arg)
   (interactive "P")
-  (notmuch-mua-send-common arg 't))
+  (notmuch-mua-send-common arg 't)
+  (notmuch-select-previous-notmuch-buffer))
 
 (defun notmuch-mua-send (&optional arg)
   (interactive "P")
@@ -560,7 +562,8 @@ unencrypted.  Really send? "))))
 
 (defun notmuch-mua-kill-buffer ()
   (interactive)
-  (message-kill-buffer))
+  (message-kill-buffer)
+  (notmuch-select-previous-notmuch-buffer))
 
 (defun notmuch-mua-message-send-hook ()
   "The default function used for `notmuch-mua-send-hook', this
diff --git a/emacs/notmuch-tree.el b/emacs/notmuch-tree.el
index d4d40761..64706397 100644
--- a/emacs/notmuch-tree.el
+++ b/emacs/notmuch-tree.el
@@ -531,10 +531,12 @@ Shows in split pane or whole window according to value of
     (notmuch-tree-next-matching-message)))
 
 (defun notmuch-tree-quit ()
-  "Close the split view or exit tree."
+  "Close the split view or exit tree. When exit from tree, select the
+previous notmuch buffer"
   (interactive)
   (unless (notmuch-tree-close-message-window)
-    (kill-buffer (current-buffer))))
+    (kill-buffer (current-buffer))
+    (notmuch-select-previous-notmuch-buffer)))
 
 (defun notmuch-tree-close-message-window ()
   "Close the message-window. Return t if close succeeds."
-- 
2.12.2