Resent Header Fields
These headers can be added to an email when it is resent by the original recipient to somebody else. These headers are Resent-Date:, Resent-From:, Resent-Sender:, Resent-To:, Resent-Cc:, Resent-Bcc: and Resent-Message-ID:. The Resent fields are strictly informational. They shouldn't be used in the normal processing of replies or other such automatic actions on messages.