We have two interconnected Exchange organizations: Exchange 2003 and Exchange 2013. When users ask for read receipt in Outlook these receipts are delivered correctly within each organization. However when Exchange 2003 users send messages to Exchange 2013 users the read receipts are delivered to the Exchange 2013 recipients and instead of the message senders. We analyzed the message content at the recipient side and it looks like the message arrives with an incorrect ReadReceiptEntryID field. The field must contain the sender's address but it contains the recipient address instead. What can be the cause of the issue?