(interactive "sNotmuch show: \nP")
   (let ((buffer-name (generate-new-buffer-name
                      (or buffer-name
-                         (concat "*notmuch-" thread-id "*")))))
+                         (concat "*notmuch-" thread-id "*"))))
+       ;; We override mm-inline-override-types to stop application/*
+       ;; parts from being displayed unless the user has customized
+       ;; it themselves.
+       (mm-inline-override-types
+        (if (equal mm-inline-override-types
+                   (eval (car (get 'mm-inline-override-types 'standard-value))))
+            (cons "application/*" mm-inline-override-types)
+          mm-inline-override-types)))
     (switch-to-buffer (get-buffer-create buffer-name))
     ;; No need to track undo information for this buffer.
     (setq buffer-undo-list t)