+(defcustom notmuch-show-depth-limit nil
+ "Depth beyond which message bodies are displayed lazily.
+
+If bound to an integer, any message with tree depth greater than
+this will have its body display lazily, initially
+inserting only a button.
+
+If this variable is set to nil (the default) no such lazy
+insertion is done."
+ :type '(choice (const :tag "No limit" nil)
+ (number :tag "Limit" 10))
+ :group 'notmuch-show)
+