+
+ (while (or (and (search-forward boundary nil t)
+ (setq truncated nil end (match-beginning 0)))
+ ;; If the boundary does not appear at all,
+ ;; the message was truncated.
+ ;; Handle the rest of the truncated message
+ ;; (if it isn't empty) by pretending that the boundary
+ ;; appears at the end of the message.
+ (and (save-excursion
+ (skip-chars-forward "\n")
+ (> (point-max) (point)))
+ (setq truncated t end (point-max))))