note not recorded when Po is approved from email notification

We use workflow for PO approvals. THe notification is send by the system as an email and the user just approves from that notification without loggin in the application (as guest). Sometime they write a note in the email which does not get updated in the syatem so the 'Notes' field is blank.

Is their a way to get this working so the 'Notes' field get the information from the body of the email.

Thanks