The details you send as part of the GET/api/order/:id method in the recipient_details field of the recipients field.

FieldDescription
nameThe name of your recipient
emailThe full email address of your recipient
phone_numberThe phone number of your recipient
delivery_addressAn array containing the address of the recipient. You can find more information about the information contained in this value here
email_messageThe message that gets attached to your gifting email and page
delivery_notesAny notes assigned to the delivery