instead of `current-time'.
                                          tembuf))
                      (error "Sending failed; SMTP protocol error"))
                (error "Sending failed; no recipients"))
-           (let* ((file-data (concat 
+           (let* ((file-data (concat
                               smtpmail-queue-dir
-                                  (mapconcat
-                                       (lambda (arg) (format "%x" arg))
-                                       (current-time) "")))
+                              (concat (time-stamp-yyyy-mm-dd)
+                                      "_" (time-stamp-hh:mm:ss))))
                   (file-elisp (concat file-data ".el"))
                   (buffer-data (create-file-buffer file-data))
                   (buffer-elisp (create-file-buffer file-elisp))