(set-rmail-inbox-list): Error if not in Rmail mode.

1 files changed, 4 insertions, 0 deletions

diff --git a/lisp/mail/rmailmsc.el b/lisp/mail/rmailmsc.el
index 98926d8117e..ad302785358 100644
--- a/lisp/mail/rmailmsc.el
+++ b/lisp/mail/rmailmsc.el
@@ -30,6 +30,10 @@
 You can specify one file name, or several names separated by commas.
 If FILE-NAME is empty, remove any existing inbox list."
   (interactive "sSet mailbox list to (comma-separated list of filenames): ")
+
+  (unless (eq major-mode 'rmail-mode)
+    (error "set-rmail-inbox-list works only for an Rmail file"))
+
   (save-excursion
     (let ((names (rmail-parse-file-inboxes))
           (standard-output nil))