Original-Recipient

This header field is present in MDN messages (MDN = Message Delivery Notification) If the email is modified while in transit such that the recipient email address is changed, a server may (and should) add the Original-Recipient header field. The email address listed in Original-Recipient field should be identical to the address originally specified by the sender. The format of the field is "Address_Type; Email_Address". The Address_Type will normally be "rfc822".

Example:

Original-Recipient: rfc822; matt@chilkatsoft.com