+(defun message-delete-not-region (beg end)
+ "Delete everything in the body of the current message that is outside of the region."
+ (interactive "r")
+ (save-excursion
+ (goto-char end)
+ (delete-region (point) (progn (message-goto-signature)
+ (forward-line -2)
+ (point)))
+ (insert "\n")
+ (goto-char beg)
+ (delete-region beg (progn (message-goto-body)
+ (forward-line 2)
+ (point))))
+ (message-goto-signature)
+ (forward-line -2))
+