(message-carefully-insert-headers headers)))
(defcustom message-header-synonyms
- '((To Cc Bcc))
+ '((To Cc Bcc)
+ (Original-To))
"List of lists of header synonyms.
E.g., if this list contains a member list with elements `Cc' and `To',
then `message-carefully-insert-headers' will not insert a `To' header