Publishing Exchange 2013 Web Services (EWS) to clients on the external network is essential for Lync 2013 Unified Contact Store (UCS) and Lync 2013 Mobile clients to work properly. Without EWS available to clients on external networks, Lync 2013 Mobile clients will be unable to get Lync contacts when UCS has been enabled for users, since these contacts are now stored in Exchange. Lync 2013 Mobile clients will also not be able to retrieve calendaring information to join Lync online meetings. In order to enable these functions for the full Lync mobile experience, EWS must be published. This article provides configuration details for publishing Exchange 2013 EWS using Forefront TMG2010. Note that TMG2010 is no longer available for purchase but Forefront Unified Access Gateway (UAG) with Service Pack 3 (SP3) is still available and can be used for publishing Exchange 2013.
To begin use the "Publish Exchange Web Client Access" in the TMG 2010 Task pane to start the wizard. Give the rule a name and in the Select Services screen choose "Exchange Server 2010" and click on "Outlook Anywhere".
Next we can either choose to publish a single Exchange CAS server, which is the case in this lab, or if an array of CAS servers are deployed then the publishing type should be set to a server farm. Then we select to use SSL for the connection from TMG to CAS: