Jul 29, 2014 · Make sure /Autodiscover/* and /EWS/* virtual directories in ISA/TMG are published as such. Wildcard certificates used for Exchange Web Services will stop Exchange integration for Lync Phone Edition devices. In extreme cases you may need to reset your Exchange virtual directories for AutoDiscover and/or EWS. Jun 01, 2018 · To verify that you are experiencing this issue, use the Test-OAuthConnectivity cmdlet. For example, connect to Remote PowerShell to Office 365 and run Test-OAuthConnectivity -Service EWS -TargetUri https://<On-Premises EWS URL>/ews/Exchange.asmx -Mailbox <Cloud Mailbox> If your scenario is a match, this cmdlet will generate the following response:

To create and configure an Exchange Web Services (EWS) connection: Start the Riva Manager application. On the menu bar, select Setup. In the left pane, select Microsoft Office 365, Microsoft Exchange 2016, Microsoft Exchange 2013, Microsoft Exchange 2010, or Microsoft Exchange 2007 to open the corresponding connection wizard.