Outlook with Outlook Connector is removing References: Header. This breaks the message threading and is a major issue. The problem does not happen with World Client. Send an email to someone using World Client, they respond using Outlook Connector, check the email headers of the received message. References Header is missing. This also causes issues when emailing support tickets. Each reply to a support ticket email that does not have the original References Header value is assumed to be a new email / new ticket. This is very undesirable.