I changed the AD attributes of a user to reflect new name and also display name and mailbox name. However the Old emails still show her old name in the To: field on received messages. So when she forwards email it comes up with that name. What must I do to change the name of these documents in the inbox??

Based on my research, "To" field cannot be modified I simulated your environment on my local VM, I used MFCMAPI tool to change the attribute of message, and all others can be changed, like "From", "Subject", except for "To" field. This attribute may be considered as hard code info for a message. And this action would involve too much effort if you can change it as a batch