(defun set-rmail-inbox-list (file-name)
"Set the inbox list of the current RMAIL file to FILE-NAME.
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))
(if (or (not names)
(y-or-n-p (concat "Replace "
(mapconcat 'identity names ", ")
"? ")))
(let ((buffer-read-only nil))
(widen)
(goto-char (point-min))
(search-forward "\n\^_")
(re-search-backward "^Mail" nil t)
(forward-line 0)
(if (looking-at "Mail:")
(delete-region (point)
(progn (forward-line 1)
(point))))
(if (not (string= file-name ""))
(insert-before-markers "Mail: " file-name "\n"))))))
(setq rmail-inbox-list (rmail-parse-file-inboxes))
(rmail-show-message rmail-current-message))